Forming a larger display using multiple smaller displays

ABSTRACT

A display system includes a first display device having an active display region having individually controllable pixels, a sensor to generate information that is useful for determining a position of the first display device relative to a second display device, and a display controller to determine the position of the first display device relative to the second display device based on the information generated by the sensor. The display controller determines an image to be shown on the first display device based on the position of the first display device relative to the second display device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims priority to U.S. patentapplication Ser. No. 15/398,693, filed on Jan. 4, 2017, which claimspriority to U.S. provisional application 62/274,764, filed on Jan. 4,2016. The entire contents of the above applications are incorporated byreference.

FIELD OF INVENTION

This description relates to forming a larger display using multiplesmaller displays.

BACKGROUND

Flat panel displays can be used in, e.g., mobile phones, tabletcomputers, desktop monitors, and televisions. Computer monitors andtelevision displays can have specific dimensions, such as havingdiagonal screen sizes of, e.g., 18, 24, 30, 46, 55, 65, or 70 inches.The displays can have specific native resolutions, such as, e.g.,640×480 (VGA display), 800×640 (SVGA display), 1024×768 (XGA display),1280×1024 (SXGA display), 1600×1200 (UXGA display), 2560/1600 (WQXGAdisplay), 3840/2160 (4K display), 5120×2880 (5K display), and 7680/4320(8K Ultra High Definition Display). Each flat panel display has anactive display area having an array of pixels. The active display areais surrounded by a display frame that provides support and protectionfor the active display area. The display frame may include a backplanethat extends across the entire back side of the active display region,and side bezels that surround the sides of the active display region.Various types of flat panel displays are available on the market,including, e.g., plasma displays, electroluminescent displays (ELDs),liquid crystal displays (LCDs), organic light emitting diodes (OLED)displays, quantum dot displays, interferometric modulator displays,carbon nanotube-based displays, digital micro shutter displays, andE-ink displays.

A computer can have a display controller that controls two or more flatpanel displays so that images can be shown on the displays. For example,when two displays are used with a computer, the two displays can beconnected to the computer directly using two video cables (e.g., VGA,DisplayPort, or HDMI cables), or the two displays can be connected tothe computer in a daisy-chain manner using, e.g., multi-streamtechnology. The computer may provide a user interface to allow a user todesignate which of the two displays is placed on the left side and whichof the two displays is placed on the right side so that images can becorrectly shown on the two displays. When three displays are used, thethree displays may be connected to the computer directly using threevideo cables, or the three displays can be connected to the computer ina daisy-chain manner using, e.g., multi-stream technology. The computermay provide a user interface to allow the user to designate which of thethree displays is placed on the left side, which of the three displaysis placed at the center, and which of the three displays is placed onthe right side so that images can be correctly shown on the threedisplays.

SUMMARY

This document describes a display system for showing images having highresolutions by forming a larger display using a group of smallerdisplays. The image contents shown on the smaller displays aredetermined based on relative positions of the smaller displays. Theoverall size and resolution of the larger display can be dynamicallyadjusted by adding displays to or removing displays from the group ofdisplays. The size and resolution of the larger display can be increasedindefinitely by adding more smaller displays to the group of displays. Alarge display having dimensions comparable to a physical windowinstalled in a house or office can be produced cost effectively. Thelarge display can show life-size images, producing a visual effectcomparable to the physical window and offering the user a “virtualwindow” for viewing scenes in other places. The display areas ofportable devices can be conveniently increased by positioning additionaldisplays adjacent to the displays of the portable devices.

This document describes a computer server that can generate imagessuitable for the larger displays each formed by multiple smallerdisplays. The computer server can communicate with the displaycontrollers of the larger displays to obtain information about thecharacteristics of the larger displays, such as the dimensions, aspectratios, and resolutions, and generate large images havingcharacteristics that are compatible with those of the larger displays.The computer server can generate the large images based on a combinationof multiple smaller images that are captured by cameras, or based oncomputer-generated imagery (CGI) techniques. The computer server mayhave databases of physical models of objects, and render high resolutionimages of scenes that include the objects based on simulation.

This document describes a computer server that can select images basedon characteristics of multiple displays that are placed in the vicinityof one another. For example, the computer server can be used torecommend images to be shown on displays that function as digitalposters. The computer server may communicate with the display controllerthat controls the images shown on the displays, such as the number ofdisplays and the relative positions of the displays. The computer servermay select, from among a collection of images, images that have similarcolor palette, similar subject matter, or form interesting visualeffects when shown on the multiple displays. Let's assume a user has agroup of four displays mounted side by side horizontally on a wall. Thecomputer server may select four images that have similar color palette,similar subject matter, or form interesting visual effects when shown onthe four displays, and send the four images to the four displays. Thefour images can be, e.g., four photos of sunset (or beach or forest)scenery, four photos of flowers that have similar colors, four photos ofvarious types of dogs, four photos of babies, four photos of athletes(e.g., baseball, soccer, or football players), or four images ofdrawings or paintings from the same artist (e.g., Monet, Picasso, or M.C. Escher). For example, the computer server may select four photos of aperson taken at various ages (e.g., at ages 1, 3, 7, and 13) and sendthose photos to the four displays such that the photos taken fromyounger to older ages are shown from left to right sequentially.

This document describes a system for showing primary and auxiliarycontents on multiple displays. For example, a user may watch televisionprograms on a television display. If the user is interested in knowingabout the bios of actors or actresses, the user can place a seconddisplay near the television, and the bios of actors of actresses can beshown on the second display without taking up screen area of thetelevision display. If the user wants to see more information, such as amap of the location where the story of the TV program takes place, theuser can place a third display near the television or near the seconddisplay, and the map can be shown on the third display. For example, theuser may view web pages on a computer display. The user may subscribe toa magazine, and the producer of the magazine may provide a seconddisplay to the user. When the user visits the web site of the magazine,the user can place the second display near the computer display, andprimary contents (e.g., articles) of the magazine will be shown on thecomputer display while secondary contents (e.g., sponsored contents)will be shown on the second display. This way, the secondary contents donot have to compete with the primary contents for screen space, allowingthe user to have a good experience when viewing the primary contents,while also having the opportunity to gain useful information from thesecondary contents.

This document describes a system having dynamically adjustable displaysfor helping students learn various subjects and complete homeworkassignments. For example, an assignment may require a student to reviewarticles on multiple web sites, analyze the contents of multiplearticles, and write a report based on the results of the analyses. Thestudent may use a small laptop computer that is convenient for carryingto and from school. The small display screen may only be sufficientlylarge to show one article at a time with a font size that is easy forviewing. The system enables the student to position one or moreadditional displays adjacent to the laptop display to form a largerdisplay. The student can view multiple articles or multiple web pagesside by side to compare and analyze the contents of the articles or webpages, and write a report that is shown side by side with the articles.Showing more learning material simultaneously on the larger display maybe helpful to learning because there is less interruption due tofrequent switching among articles and reports that may be required ifonly the small laptop screen were used. When performing comparativeanalyses of the articles and writing a report based on the analyses onthe small laptop screen, the student may have to navigate and switchamong the articles and the report multiple times (which takes somecognitive effort), so that it may take a longer time for the student tounderstand and remember a subject, as compared to using the largerdisplay.

For example, the student can read articles related to a geographicalregion while also viewing a map of the geographical region andadditional statistics of the geographical region, in which the articles,the map, and the statistics are shown side by side on the largerdisplay. The student can work on math drills shown on a portion of thelarger display (e.g., by typing in the answers or entering the answersusing a stylus if the laptop display or one of the additional displaysis a touch screen), and also look up additional information related tothe math subject on another portion of the larger display. The studentcan learn to write computer programs in which a first portion of thelarger display shows the code written by the student, a second portionof the larger display shows the results from executing the code, and athird portion of the larger display shows a tutorial on computerprogramming.

This document describes displays having transparent borders thatpartially overlap other displays to form a larger display without darklines between the displays. A second display panel having a transparentborder can overlap a first display panel to form a larger display suchthat an image can be shown across the first and second display panels.By using a transparent border for the second display panel, the pixelsof the first display panel that are covered by the transparent bordercan be seen by a user, so the pixels of the first display panel coveredby the transparent border appear to be adjacent to the pixels of thesecond display panel without any gap or dark line between the pixels ofthe first and second display panels.

The transparent border may not be completely transparent to visiblelight emitted from pixels of the first display panel and may besemi-transparent such that the brightness of the pixels of the firstdisplay covered by the semi-transparent border is reduced. Thebrightness of the pixels of the first display covered by thesemi-transparent border can be enhanced to compensate for the reductionin brightness caused by the semi-transparent border. If thesemi-transparent border changes the color of the light passing throughthe semi-transparent border, the color of the pixels of the firstdisplay covered by the semi-transparent border can be adjusted tocompensate for the color-changing effects caused by the semi-transparentborder.

In some implementations, the second display panel can have light sensorson a back side of the display panel to detect light emitted from pixelsof the first display panel when the second display panel overlaps thefirst display panel. For example, the second display panel can include asubstrate, and organic light emitting diode (OLED) pixels are formed ona front side of the substrate. Each OLED pixel includes an OLED and athin film transistor (TFT) for driving the OLED. The light sensors canbe formed on a back side of the substrate. A control module, which mayinclude a timing controller, a column driver, and/or a row driver, mayalso be formed on the back side of the substrate. The OLED pixels can beelectrically coupled to the controller by column lines and row lines inwhich the ends of the column and row lines are electrically coupled tosignal lines on the back side of the substrate through through-holes inthe substrate, and the signal lines on the back side of the substrateare electrically coupled to the control module.

In another example, the OLED pixels are formed on a first side of afirst substrate, the light sensors are formed on a first side of asecond substrate, and a second side of the first substrate is bonded toa second side of the second substrate.

The active display region can include transparent pixels. For example,the transparent pixels may be located adjacent to the transparent orsemi-transparent border region. When two display panels overlap, somepixels in the upper display panel are active to show content, somepixels in the upper display panel are transparent to allow the activepixels in the lower display panel to be visible. For example,juxtaposing the active pixels in the upper and lower display panels canprovide a jagged boundary for the upper display panel so that the userdoes not see a straight line between the two display panels. Thetransparent display portion can be, e.g., 50, 100, or 200 pixels wide.Which pixels of the upper display panel are active may depend on thecontent. The boundary between the active pixels and the transparentpixels in the upper display panel may follow the contour of displayedimages so that the boundary is less visible and blends with the images.For example, if leaves are shown in the transparent display portion, theboundary between active and transparent pixels may follow the contour ofthe leaves.

In a general aspect, a display system comprises: a first display devicecomprising an active display region comprising individually controllablepixels; a sensor to generate information that is useful for determininga position of the first display device relative to a second displaydevice; and a display controller to determine the position of the firstdisplay device relative to the second display device based on theinformation generated by the sensor, and determine an image to be shownon the first display device based on the position of the first displaydevice relative to the second display device.

Implementations can include one or more of the following features. Thefirst display device can comprise a transparent or semi-transparentborder region having a transmissivity of at least 10% for visible light.

The display controller can control the pixels of the active displayregion of the first display device to show a first image that is anextension of a second image shown on the second display when the firstdisplay overlaps the second display at the semi-transparent borderregion.

The sensor can comprise one or more light sensors on a backside of thedisplay device for detecting light from the second display device, andthe display controller uses outputs from the one or more light sensorsto determine the position of the first display device relative to thesecond display device.

The sensor can comprise a camera for capturing images shown on the firstand second display devices, and the display controller uses imagescaptured by the camera to determine the position of the first displaydevice relative to the second display device.

The sensor can generate information that is useful for determining theposition of the first display device relative to the second displaydevice display from time to time, and the controller dynamically updatesthe image shown on the first display device based on the informationgenerated by the sensor.

The display system can include a motion sensor that is configured todetect movements of the first display device, in which in response tothe motion sensor detecting a movement of the first display device, thedisplay controller is configured to determine an updated position of thefirst display device relative to the second display device, anddetermine an image to be shown on the first display device based on theupdated position of the first display device relative to the seconddisplay device.

In another general aspect, a ship comprises: a first display devicecomprising an active display region comprising individually controllablepixels; a sensor to generate information that is useful for determininga position of the first display device relative to a second displaydevice; a display controller to determine the position of the firstdisplay device relative to the second display device based on theinformation generated by the sensor, and determine an image to be shownon the first display device based on the position of the first displaydevice relative to the second display device; and a first camera tocapture images of an environment of the ship, in which the displaycontroller causes at least portions of the images of the environment ofthe ship to be shown on the first display device.

Implementations can include one or more of the following features. Thefirst display device can include a transparent or semi-transparentborder region having a transmissivity of at least 10% for visible light.

The display controller can control the pixels of the active displayregion of the first display device to show a first image that is anextension of a second image shown on the second display when the firstdisplay overlaps the second display at the semi-transparent borderregion.

The sensor can include one or more light sensors on a backside of thedisplay device for detecting light from the second display device, andthe display controller uses outputs from the one or more light sensorsto determine the position of the first display device relative to thesecond display device.

The sensor can include a second camera for capturing images shown on thefirst and second display devices, and the display controller uses imagescaptured by the second camera to determine the position of the firstdisplay device relative to the second display device.

The sensor can generate information that is useful for determining theposition of the first display device relative to the second displaydevice display from time to time, and the controller can dynamicallyupdate the image shown on the first display device based on theinformation generated by the sensor.

The ship can include multiple smaller displays that collaboratively forma larger display, in which the display controller can be configured todetermine the position of each of the display device relative to atleast one other display device, and determine an image to be shownacross the multiple smaller displays based on the relative positions ofthe smaller displays.

The larger display can be configured to show images that representscenes outside of the ship.

In another general aspect, an apparatus comprises a first display devicecomprising a first active display region comprising individuallycontrollable pixels; and a transparent or semi-transparent border regionhaving a transmissivity of at least 10% for visible light. The apparatuscomprises a second display device comprising a second active displayregion comprising individually controllable pixels, in which the firstdisplay device overlaps the second display device such that thetransparent or semi-transparent border region of the first displaydevice covers at least a portion of the second active display region.The apparatus comprises a display controller to control the first andsecond display devices to show an image that spans the first and seconddisplay devices.

Implementations can include one or more of the following features. Thedisplay controller can be configured to control the second displaydevice to modify a property of pixels in the second active displayregion that is covered by the semi-transparent border region of thefirst display device to compensate a visual effect caused by thesemi-transparent border region.

The display controller can be configured to control the second displaydevice to increase a brightness of pixels in the second active displayregion that is covered by the semi-transparent border region of thefirst display device to compensate a reduction in brightness of thepixels due to being covered by the semi-transparent border region.

The apparatus can include a sensor to detect a position of the firstdevice relative to the second display device, in which the displaycontroller is configured to control the first and second display devicesbased on information about the relative positions of the first andsecond devices.

The sensor can include a camera that captures an image of at least aportion of the pixels of the second display device adjacent to thesemi-transparent border region and not covered by the semi-transparentborder region, and a portion of the pixels of the first display deviceadjacent to the semi-transparent border region.

In another general aspect, a system for assisting in learning isprovided. The system includes a larger display formed by two or moresmaller displays, each of the smaller displays includes an activedisplay region having individually controllable pixels. The systemincludes at least one sensor to generate sensing signals havinginformation useful in determining relative positions of the smallerdisplays; and a display controller configured to determine relativepositions of the smaller displays based on the sensing signals generatedby the at least one sensor, determine a larger image for the largerdisplay, and control each of the smaller displays to show a portion ofthe larger image such that the larger image spans across the smallerdisplays. A first portion of the image represents a first learningmaterial, and a second portion of the image represents a second learningmaterial related to the first learning material.

Implementations can include one or more of the following features. Afirst smaller display can be oriented at an angle relative to a secondsmaller display such that an x-axis of the first smaller display is notparallel to an x-axis of the second smaller display. The displaycontroller can be configured to determine the relative angle between thex-axis of the first smaller display relative to the x-axis of a secondsmaller display, the angle being greater than 0 and less than 90degrees, and determine the portion of the larger image to show on atleast one of the first or second smaller display taking into account ofthe relative angle between the first and second smaller displays.

When a first smaller display moves relative to a second smaller display,the display controller can automatically determine the relativepositions of the first and second smaller displays based on the sensingsignals generated by the at least one sensor, and control each of thefirst and second smaller displays to show a portion of the larger imagesuch that the larger image spans correctly across the first and secondsmaller displays.

Each of the smaller displays can include a transparent orsemi-transparent border region having a transmissivity of at least 10%for visible light, in which the transparent or semi-transparent borderregion of a first smaller display device can overlap a second smallerdisplay such that the transparent or semi-transparent border region ofthe first smaller display covers at least a portion of the activedisplay region of the second smaller display.

The display controller can be configured to control the second smallerdisplay to modify a property of pixels of the second smaller displaythat is covered by the transparent or semi-transparent border region ofthe first smaller display to compensate a visual effect caused by thetransparent or semi-transparent border region.

The display controller can be configured to control the second smallerdisplay to increase a brightness of pixels of the second smaller displaythat is covered by the transparent or semi-transparent border region ofthe first smaller display to compensate a reduction in brightness of thepixels due to being covered by the transparent or semi-transparentborder region.

The at least one sensor can include one or more light sensors on abackside of a first smaller display for detecting light from a secondsmaller display, and the display controller can use outputs from the oneor more light sensors to determine the position of the first smallerdisplay relative to the second smaller display.

The at least one sensor can include a camera that captures an image ofpixels of the smaller displays, and the display controller can useoutputs from the camera to determine the relative positions of thesmaller displays.

The first learning material can include mathematical exercises, and thesecond learning material can include at least one article related to themathematical exercises.

The first learning material can include a timeline of events, and thesecond learning material can include at least one article related to theevents.

The first learning material can include at least one mathematicalformula, and the second learning material can include at least one graphrelated to the at least one mathematical formula.

The first learning material can include at least one of a foreignlanguage article or a foreign language exercise, and the second learningmaterial can include at least one of a foreign language dictionary, aforeign language thesaurus, or a foreign language grammar guide.

The first learning material can include at least one map of ageographical region, and the second learning material can include atleast one article related to the geographical region.

In another general aspect, an apparatus comprises: a first display panelhaving a first active display region; a second display panel having asecond active display region and a transparent or semi-transparentborder region; a first connector to connect the first display panel to abase; and a second connector to connect the second display panel to thebase, in which the second connector is adjustable to move the seconddisplay panel to one of a first position and a second position, and whenthe second display panel is at the second position, at least a portionof the transparent or semi-transparent border region overlaps a portionof the first active display region; wherein when the second displaypanel is at the second position, the first and second active displayregions are configured to show an image that spans a portion of thefirst active display region under the transparent or semi-transparentborder region and a portion of the second active display region adjacentto the transparent or semi-transparent border region.

Implementations can include one or more of the following features. Thesecond connector can include a motorized arm that is configured to movethe second display panel between the first position and the secondposition.

When the second display panel is at the first position, the overlapbetween the first and second display panels can be greater than theoverlap between the first and second display panels when the seconddisplay panel is at the second position.

When the second display panel is at the first position, the seconddisplay panel can be behind the first display panel, and when the seconddisplay panel is at the second position, the second display panel can bein front of the first display panel.

The second connector can include a swivel arm that enables the seconddisplay panel to be moved from the first position behind the firstdisplay panel to the second position in front of the first displaypanel.

The second display panel can have a non-transparent border region, andthe transparent or semi-transparent border region is thinner than thenon-transparent border region.

The first display panel can include at least one of a liquid crystaldisplay, an organic light emitting diode display, an electronic inkdisplay, a plasma display, an electroluminescent display, asurface-conduction electron-emitter display, a field emission display,an interferometric modulator display, or a quantum dot display.

The second display panel can include at least one of a liquid crystaldisplay, an organic light emitting diode display, an electronic inkdisplay, a plasma display, an electroluminescent display, asurface-conduction electron-emitter display, a field emission display,an interferometric modulator display, or a quantum dot display.

The second display panel can include: a sensor disposed at a backside ofthe display panel to sense a parameter of the first display panel andgenerate a sensor output signal, and a control module to determine aposition of the second display panel relative to the first display panelbased on the sensor output signal.

The sensor can include a light sensor to sense light emanating from thefirst display panel.

When the second display panel is at the second position, the lightsensor can face a portion of the first active display region.

The control module can control the first display panel to activatedifferent pixels at different times, each time activating one or morepixels, and the light sensor is configured to sense light from the oneor more of the activated pixels.

The control module can determine the relative positions of the first andsecond display panels based on the position or positions of one or morepixels that are activated when the light sensor senses light or senses achange in color or brightness.

A left side of the second display panel can overlap a right side of thefirst display panel, the control module can control the first displaypanel to sequentially activate a vertical line of pixels starting fromthe right border, and scan the vertical line toward the left side untilthe light sensor detects light from the activated line of pixels.

The control module can determine the relative positions of the first andsecond display panels based on the position of the activated line ofpixels when the light sensor detects light from the activated line ofpixels.

The sensor can include a plurality of light sensors at various positionsto sense light emanating from the first display panel.

The control module can control the first display panel to sequentiallyactivate different pixels, each time activating one or more pixels, andthe light sensors are configured to detect light from the one or moreactivated pixels.

The control module can determine the relative positions of the first andsecond display panels based on the position or positions of theactivated one or more pixels when the light sensors detect light fromthe one or more activated pixels.

The control module can control the first display panel to activatedifferent pixels at different times, each time activating one or morepixels, and determine the relative positions of the first and seconddisplay panels based on the sensor output signals from the light sensor.

The apparatus can include a camera to take images of the first andsecond display panels, and a control module to determine a position ofthe second display panel relative to the first display panel based onthe images taken by the camera.

The second connector can include a swivel arm to move the second displaypanel between the first and second positions, and a stop mechanism tostop the swivel arm at the second position, in which the second positionis a predetermined position, and the relative positions between thefirst and second displays are known when the second display panel is atthe second position.

The apparatus can include a control module to control the first andsecond display panels to display an image that spans the first andsecond active display areas, in which the portion of the image shown onthe second active display area is based on the relative positionsbetween the first and second displays.

The apparatus can include a control module configured to control thefirst and second display panels to display an image that spans the firstand second active display areas, in which the portion of the image shownon the second active display area is based on the relative positionsbetween the first and second displays.

The control module can be configured to control the first and seconddisplay panels to display a line that spans the first and second activedisplay areas, in which a first portion of the line is shown by pixelsin the first active display area not covered by the transparent orsemi-transparent border region of the second display panel, a secondportion of the line is shown by pixels in the first active display areacovered by the transparent or semi-transparent border region, and athird portion of the line is shown by pixels in the second activedisplay area.

The control module can be configured to control the first and seconddisplay panels to display the first portion of the line, the secondportion of the line, and the third portion of the line to form acontinuous line that spans the first and second active display regions.

The line can include at least one of a border of a window shown acrossthe first and second active display regions, a feature of a face shownacross the first and second active display regions, a feature of anobject shown across the first and second active display regions, or aborder of a geometric shape shown across the first and second activedisplay regions.

The first and second display panels can show at least one of atwo-dimensional or three-dimensional image that spans the first andsecond active display regions.

The first and second display panels can each include a two-dimensionaldisplay configured to display two-dimensional images.

The first and second display panels can each include a three-dimensionaldisplay configured to display three-dimensional images.

When the second display panel is at the first position, the seconddisplay panel can be in front of the first display panel and cover afirst portion of the first active display region, when the seconddisplay panel is at the second position, the second display panel canalso be in front of the first display panel and cover a second portionof the first active display region, and the first portion is larger thanthe second portion.

Which when the second display panel is at the first position, the seconddisplay panel can completely cover the first active display region.

When the second display panel is at the second position, the secondactive display region can be at the right side of the first activedisplay region.

When the second display panel is at the second position, the secondactive display region can be at the left side of the first activedisplay region.

When the second display panel is at the second position, the secondactive display region can be below the first active display region.

When the second display panel is at the second position, the secondactive display region can be above the first active display region.

At least one of the first or second active display region can have arectangular shape.

At least one of the first or second active display region can have anon-rectangular shape.

At least one of the first or second active display region can have ashape in the form of a circle, an oval, a triangle, a rhombus, aparallelogram, a trapezium, a convex polygon, a concave polygon, or anirregular shape.

Each of the first and second active display regions can have a pluralityof pixels.

In another general aspect, an apparatus comprises: a first display panelhaving a first active display region; a second display panel having asecond active display region and a transparent or semi-transparentborder region; a sensor to sense a parameter that is indicative of aposition of the second display panel relative to the position of thefirst display panel and generate a sensor output signal; and a controlmodule to control the first and second active display regions such thatwhen the control module detects that the second display panel overlapsthe first display panel such that the transparent or semi-transparentborder region covers a portion of the first active display region, thefirst and second active display regions show an image that spans aportion of the first active display region behind the transparent orsemi-transparent border region and a portion of the second activedisplay region adjacent to the transparent or semi-transparent borderregion.

Implementations can include one or more of the following features. Thesecond display panel can have a non-transparent border region, and thetransparent or semi-transparent border region has a thickness that isless than a thickness of the non-transparent border region, thethickness being measured in a direction orthogonal to the surface of thesecond active display region.

The second display panel can have a center region that has a thicknessthat is greater than the thickness of the transparent orsemi-transparent border region, the thickness being measured in adirection orthogonal to the surface of the second active display region.

The second display panel can have a cross-sectional thickness profilethat is thinner at the transparent or semi-transparent border region andgradually becomes thicker toward the center of the display panel.

The second display panel can include a concave surface region and aconvex surface region.

The concave surface region can be closer to the transparent orsemi-transparent border region than the convex surface region.

The center region of the second display panel can include electroniccircuitry for driving pixels of the second active display region.

The electronic circuitry can include at least one of a column driver, arow driver, a timing controller, dynamic random access memory, staticrandom access memory, flash memory, magnetoresistive random-accessmemory, phase-change memory, resistive random-access memory,programmable metallization cell, conductive-bridging random accessmemory, a memristor, a solid state drive, an electromechanical magneticdisk, power supply circuitry, communication circuitry, circuitry fordriving the sensor, circuitry for processing the sensor output signal,the control module, or a data processor.

The first display panel can include at least one of a liquid crystaldisplay, an organic light emitting diode display, an electronic inkdisplay, a plasma display, an electroluminescent display, asurface-conduction electron-emitter display, a field emission display,an interferometric modulator display, or a quantum dot display.

The second display panel can include at least one of a liquid crystaldisplay, an organic light emitting diode display, an electronic inkdisplay, a plasma display, an electroluminescent display, asurface-conduction electron-emitter display, a field emission display,an interferometric modulator display, or a quantum dot display.

The sensor can include a light sensor disposed at a backside of thesecond display panel to sense light emanating from the first activedisplay region.

The control module can be configured to control the first display panelto activate different pixels at different times, each time activatingone or more pixels, and the light sensor is configured to sense lightfrom the one or more of the activated pixels.

The control module can be configured to determine the relative positionsof the first and second display panels based on the position orpositions of one or more pixels that are activated when the light sensorsenses light from the activated one or more pixels or senses a change incolor or brightness due to light from the activated one or more pixels.

The control module can be configured to control the first and seconddisplay panels to display an image that spans continuously across thefirst and second active display areas, in which the portion of the imageshown on the second active display area is based on the relativepositions between the first and second displays.

A left side of the second display panel can overlap a right side of thefirst display panel, the control module can control the first displaypanel to sequentially activate a vertical line of pixels starting fromthe right border, and scan the vertical line toward the left side untilthe light sensor detects light from the activated line of pixels.

The control module can be configured to determine the relative positionsof the first and second display panels based on the position of theactivated line of pixels when the light sensor detects light from theactivated line of pixels.

The control module can be configured to control the first and seconddisplay panels to display an image that spans continuously across thefirst and second active display areas, in which the portion of the imageshown on the second active display area is based on the relativepositions between the first and second displays.

The sensor can include a plurality of light sensors at various positionsto sense light emanating from the first display panel.

The control module can be configured to control the first display panelto activate different pixels, each time activating one or more pixels,and the light sensors are configured to detect light from the one ormore activated pixels.

The control module can be configured to determine the relative positionsof the first and second display panels based on the position orpositions of the activated one or more pixels when the light sensorsdetect light from the one or more activated pixels.

The control module can be configured to control the first and seconddisplay panels to display an image that spans continuously across thefirst and second active display areas, in which the portion of the imageshown on the second active display area is based on the relativepositions between the first and second displays.

The control module can be configured to control the portion of the firstactive display region that is behind the transparent or semi-transparentborder region to adjust at least one of a brightness, contrast, hue, orcolor to compensate effects of the border region, such that the imageappears more uniform across the portion of the first active displayregion that is not covered by the transparent or semi-transparent borderregion and the portion of the first active display region that is behindthe transparent or semi-transparent border region.

The control module can be configured to control the portion of the firstactive display region that is behind the transparent or semi-transparentborder region to increase the brightness to compensate the reduction ofbrightness of light that pass the border region, such that thebrightness of the image appears more uniform across the portion of thefirst active display region that is not covered by the transparent orsemi-transparent border region and the portion of the first activedisplay region that is behind the transparent or semi-transparent borderregion, than if the control module had not increased the brightness theportion of the first active display region that is behind thetransparent or semi-transparent border region.

The control module can be configured to control the first and secondactive display regions such that for a portion of the image that isintended to have a uniform brightness, when the portion of the image isshown spanning across the first and second active display regions, theportion of the image has a uniform brightness across the first andsecond active display regions.

The sensor can include a camera configured to take images of the firstand second display panels, and the control module is configured todetermine a position of the second active display region relative to thefirst active display region based on the images taken by the camera.

The control module can be configured to control the first and secondactive display regions to display an image that spans the first andsecond active display areas, in which the portion of the image shown onthe second active display area is based on the relative positionsbetween the first and second displays.

The control module can be configured to control the first and secondactive display regions such that the portion of the image shown on thesecond active display area is based on the relative positions betweenthe first and second displays.

The control module can be configured to control the first and secondactive display regions to display a line that spans the first and secondactive display areas, in which a first portion of the line is shown bypixels in the first active display area not covered by the transparentor semi-transparent border region of the second display panel, a secondportion of the line is shown by pixels in the first active display areacovered by the transparent or semi-transparent border region, and athird portion of the line is shown by pixels in the second activedisplay area.

The control module can be configured to control the first and secondactive display regions to display the first portion of the line, thesecond portion of the line, and the third portion of the line to form acontinuous line that spans the first and second active display regions.

The line can include at least one of a border of a window shown acrossthe first and second active display regions, a feature of a face shownacross the first and second active display regions, a feature of anobject shown across the first and second active display regions, or aborder of a geometric shape shown across the first and second activedisplay regions.

The first and second display panels can show at least one of atwo-dimensional or three-dimensional image that spans the first andsecond active display regions.

The first and second display panels can each include a two-dimensionaldisplay configured to display two-dimensional images.

The first and second display panels can each include a three-dimensionaldisplay configured to display three-dimensional images.

The three-dimensional display can include at least one of a stereoscopicdisplay or an autostereoscopic display.

The three-dimensional display can include a spatially multiplexeddisplay.

The spatially multiplexed display can include at least one of a parallaxbarrier display, a lenticular display, or a random hole display.

The three-dimensional display can include a stack of display modules.

When the second display panel is at a left side or a right side of thefirst display panel, the control module can control the first and secondactive display regions to show an image that spans horizontally acrossthe first and second active display regions.

When the second display panel is at an upper side or a lower side of thefirst display panel, the control module can control the first and secondactive display regions to show an image that spans vertically across thefirst and second active display regions.

At least one of the first or second active display region can have arectangular shape.

At least one of the first or second active display region can have anon-rectangular shape.

At least one of the first or second active display region can have ashape in the form of a circle, an oval, a triangle, a rhombus, aparallelogram, a trapezium, a convex polygon, a concave polygon, or anirregular shape.

Each of the first and second active display regions can have a pluralityof pixels.

Each of some of the pixels can include a liquid crystal cell and a thinfilm transistor.

Each of some of the pixels can include an organic light emitting diodeand a thin film transistor.

The apparatus can include a power supply that powers the second displaypanel wirelessly.

The wireless power transfer from the power supply to the second displaypanel can be based on at least one of magnetic induction, magneticresonance, resonant magnetic coupling, capacitive coupling, microwaves,ultrasound, or lasers.

The second display panel can include one or more coils to receive powerwirelessly from the power supply.

The apparatus can include solar cells or photovoltaic cells that areconfigured to provide power to the second display panel.

The second display panel can have a left side, a right side, a top side,and a bottom side, in which borders at two of the left, right, top, andbottom sides are transparent or semi-transparent.

The second display panel can have a left side, a right side, a top side,and a bottom side, in which borders at three of the left, right, top,and bottom sides are transparent or semi-transparent.

The second display panel can have a left side, a right side, a top side,and a bottom side, in which borders the left, right, top, and bottomsides are all transparent or semi-transparent.

The transparent border region can have a transmissivity of at least 90%with respect to visible light.

The semi-transparent border region can have a transmissivity of at least30% with respect to visible light.

The first display can include pixels that emit infrared light, and thesensor can be configured to detect the infrared light.

The transparent or semi-transparent region can have a transmissivity ofless than 10% with respect to infrared light.

The second display panel can include a substrate, pixels disposed on afront side of the substrate, and circuitry to drive the pixels, in whichthe circuitry can be disposed on a back side of the substrate.

The pixels can be electrically coupled to the circuitry using connectorsthat pass through through-holes formed in the substrate.

The transparent or semi-transparent border region can includetransparent or semi-transparent conductive lines.

The transparent or semi-transparent conductive lines can electricallycouple pixel circuits to circuitry for driving the pixel circuits.

The sensor can include a plurality of light sensors positioned atvarious locations on a backside of the second display panel.

Each light sensor can be associated with known position coordinates.

The light sensors can be positioned along a line.

The light sensors can be positioned along a first line and a secondline, the first line extends along a first direction, and the secondline extends along a second direction.

The first direction can be parallel to the second direction.

The first line and the second line can be spaced apart along a thirddirection orthogonal to the first direction.

The second display panel can include a motion sensor.

The control module can determine a position of the second displayrelative to the first display panel in response to the motion sensordetecting a movement of the second display panel.

Each time the motion sensor detects a movement of the second displaypanel, the control module can re-determine the position of the seconddisplay panel relative to the first display panel and update the imageshown on the second active display in response to the newly determinedposition of the second display panel relative to the first displaypanel.

The second display panel can include an adhesive or friction pad at abackside of the second display panel.

The adhesive or friction pad can be configured to reduce movementbetween the first and second display panels after the second displaypanel is positioned to overlap the first display panel.

The adhesive can include a synthetic gecko adhesive.

The adhesive can provide a temporary adhesive force to cause the seconddisplay panel to temporarily adhere to the first display panel, in whichthe second display panel can be removed from the first display panel bypulling the second display panel away from the first display panel.

The second display panel can include an electro-adhesive pad on abackside of the second display panel.

The electro-adhesive pads can include a conductive electrode depositedon a surface of a polymer.

The control module can be configured to apply a first signal to theelectro-adhesive pad to cause the electro-adhesive pad to adhere to thefirst display panel in response to a first user instruction.

The control module can be configured to apply a second signal to theelectro-adhesive pad to cause the electro-adhesive pad to be releasedfrom the first display panel in response to a second user instruction.

The control module can be configured to apply a first control signal tothe electro-adhesive pad to cause the electro-adhesive pad to adhere tothe first display panel, and in response to a motion sensor detecting amovement indicating an edge of the second display panel being pulledaway from the first display panel, the control module can be configuredto apply a second control signal to the electro-adhesive pad to causethe electro-adhesive pad to be released from the first display panel.

The control module can be configured to apply a first control signal tothe electro-adhesive pad to generate an adhesion force to cause theelectro-adhesive pad to adhere to the first display panel, and inresponse to a motion sensor detecting a movement indicating an edge ofthe second display panel being pulled away from the first display panel,the control module can be configured to apply a second control signal tothe electro-adhesive pad to cause the electro-adhesive pad to reduce aadhesion force between the electro-adhesive pad and the first displaypanel.

After the electro-adhesive pad reduces the adhesion force between theelectro-adhesive pad and the first display panel, when the controlmodule determines that the second display panel is moved to a secondposition and the electro-adhesive pad still overlaps the first displaypanel, the control module can be configured to apply a third controlsignal to the electro-adhesive pad to cause the electro-adhesive pad toincrease the adhesion force between the electro-adhesive pad and thefirst display panel.

The control module can be configured to control the electro-adhesive padto generate a first adhesive force such that when the electro-adhesivepad adheres to the first display panel, the second display panel can bepulled away from the first display panel using a force having a firstpredetermined magnitude, and the control module can be configured tocontrol the electro-adhesive pad to generate a second adhesive forcesuch that when the electro-adhesive pad adheres to the first displaypanel, the second display panel cannot be pulled away from the firstdisplay panel using a force having the first predetermined magnitude.

The second display panel can have an anti-reflective coating on a backside of the transparent or semi-transparent border region to reducereflection of light emitted from pixels of the first display panelcovered by the transparent or semi-transparent border region.

The sensor can include a series of photoreceptors and a series of lensesto focus light onto the photoreceptors.

In another general aspect, an apparatus comprises: a first display panelhaving a first active display region; a second display panel having asecond active display region and a transparent or semi-transparentborder region; wherein the second display panel overlaps the firstdisplay panel such that the transparent or semi-transparent borderregion covers a portion of the first active display region, and thefirst and second active display regions show an image that spans aportion of the first active display region behind the transparent orsemi-transparent border region and a portion of the second activedisplay region adjacent to the transparent or semi-transparent borderregion.

Implementations can include one or more of the following features. Theapparatus can include a support device that supports the first andsecond display panels at predetermined positions relative to each other.

The first display panel can include a display panel of at least one of amobile phone, a tablet computer, a notebook computer, a desktop computermonitor, a television, a game controller, or an electronic book.

In another general aspect, a method comprises: positioning a firstdisplay panel and a second display panel in which a portion of a secondactive display area of the second display panel overlaps a portion offirst active display area of the first display panel, the first activedisplay area comprising a plurality of pixels, and the second activedisplay area comprising a plurality of pixels; showing a first portionof an image of an object on the first active display area; and showing asecond portion of the image of the object on the second active displayarea, in which the image of the object spans continuously across thefirst active display area and the second active display area.

Implementations can include one or more of the following features. Themethod can include determining the second portion of the image of theobject based on a position of the second active display area relative tothe first active display area.

The method can include determining the position of the second activedisplay area relative to the first active display area using a sensor.

Determining the position of the second active display area relative tothe first active display area can include using one or more photosensors disposed on a back side of the second display panel to detectlight emitted from one or more pixels of the first active display area.

The method can include activating different pixels of the first activeregion at different times, each time activating one or more pixels, andusing the one or more photo sensors to sense light from the one or moreactivated pixels.

The method can include determining the relative positions of the firstand second active display areas based on the position or positions ofone or more pixels that are activated when the light sensor senses lightfrom the activated one or more pixels or senses a change in color orbrightness due to light from the activated one or more pixels.

Positioning a first display panel and a second display panel can includeoverlapping a left side of the second display panel on a right side ofthe first display panel, and the method can include sequentiallyactivating a vertical line of pixels in the first active display areastarting from the right border, and scan the vertical line toward theleft side until the one or more photo detectors detect light from theactivated line of pixels.

The method can include determining the relative positions of the firstand second active display areas based on the position of the activatedline of pixels when the one or more photo detectors detect light fromthe activated line of pixels.

Determining the position of the second active display area relative tothe first active display area can include using a camera facing thefirst and second active display areas to capture images of the pixels onthe first and second active display areas.

The method can include calibrating a brightness of the second activedisplay area to correspond to the brightness of the first active displayarea, including taking an image that includes a first set of pixels inthe first active display area and a second set of pixels in the secondactive display area, comparing the brightness of the first set of pixelswith the brightness of the second set of pixels, and adjust thebrightness of the second set of pixels to match the brightness of thefirst set of pixels.

The method can include calibrating a color of the second active displayarea to correspond to the color of the first active display area,including taking an image that includes a first set of pixels in thefirst active display area and a second set of pixels in the secondactive display area, comparing the color of the first set of pixels withthe color of the second set of pixels, and adjust the color of thesecond set of pixels to match the color of the first set of pixels.

The method can include mapping coordinates of a pixel in the secondactive display area to coordinates in a coordinate system of the firstdisplay panel, determining characteristics of a pixel of the image thatcorrespond to the coordinates in the first display coordinate system,and assigning the characteristics of the pixel of the image to the pixelin the second active display area.

The characteristics of a pixel can include at least one of a color orbrightness of the pixel.

Showing a second portion of the image of the object on the second activedisplay area can include showing the second portion of the image of theobject on at least one of liquid crystal cells, organic light emittingdiodes, electronic ink pixels, plasma display pixels, electroluminescentdisplay pixels, surface-conduction electron-emitter display pixels,field emission display pixels, interferometric modulators, or quantumdot display pixels.

The method can include overlapping a transparent or semi-transparentborder of the second display panel over the first active display area.

The method can include controlling the portion of the first activedisplay region that is behind the transparent or semi-transparent borderregion to adjust at least one of a brightness, contrast, hue, or colorto compensate effects of the border region, such that the image appearsmore uniform across the portion of the first active display region thatis not covered by the transparent or semi-transparent border region andthe portion of the first active display region that is behind thetransparent or semi-transparent border region.

The method can include controlling the portion of the first activedisplay region that is behind the transparent or semi-transparent borderregion to increase the brightness to compensate the reduction ofbrightness of light that pass the border region, such that thebrightness of the image appears more uniform across the portion of thefirst active display region that is not covered by the transparent orsemi-transparent border region and the portion of the first activedisplay region that is behind the transparent or semi-transparent borderregion, than if the control module had not increased the brightness theportion of the first active display region that is behind thetransparent or semi-transparent border region.

The method can include controlling the first and second active displayareas to display a line that spans the first and second active displayareas, in which a first portion of the line is shown by pixels in thefirst active display area not covered by the transparent orsemi-transparent border region of the second display panel, a secondportion of the line is shown by pixels in the first active display areacovered by the transparent or semi-transparent border region, and athird portion of the line is shown by pixels in the second activedisplay area.

The control module can be configured to control the first and secondactive display regions to display the first portion of the line, thesecond portion of the line, and the third portion of the line to form acontinuous line that spans the first and second active display regions.

The line can include at least one of a border of a window shown acrossthe first and second active display area, a feature of a face shownacross the first and second active display areas, a feature of an objectshown across the first and second active display areas, or a border of ageometric shape shown across the first and second active display areas.

The method can include controlling the first and second active displayregions such that for a portion of the image that is intended to have auniform brightness, when the portion of the image is shown spanningacross the first and second active display regions, the portion of theimage has a uniform brightness across the first and second activedisplay regions.

The method can include controlling the first and second active displayareas to display a line that spans the first and second active displayareas, in which a first portion of the line is shown by pixels in thefirst active display area and a second portion of the line is shown bypixels in the second active display area.

The method can include controlling the first and second active displayareas to display the first and second portions of the line to form acontinuous line that spans the first and second active display regions.

Showing the image on the first and second active display areas caninclude showing a three dimensional image on the first and second activedisplay areas.

Positioning a first display panel and a second display panel can includepositioning the second display on a left side of the first display, andshowing the image can include showing an image that spans horizontallyacross the first and second active display areas.

Positioning a first display panel and a second display panel can includepositioning the second display on an upper side of the first display,and showing the image can include showing an image that spans verticallyacross the first and second active display areas.

The method can include powering the second display panel wirelessly.

Powering the second display panel wirelessly can include wirelesslytransferring power from a power supply to the second display panel basedon at least one of magnetic induction, magnetic resonance, resonantmagnetic coupling, capacitive coupling, microwaves, ultrasound, orlasers.

The method can include receiving power wirelessly at the second displaypanel using coils in the second display panel.

The method can include powering the second display panel using solarcells or photovoltaic cells.

Positioning the first and second display panels can include positioninga portion of the second active display area above the first activedisplay area.

Positioning the first and second display panels can include positioninga portion of the first active display area above the second activedisplay area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of first active display area of the first displaypanel, the third active display area comprising a plurality of pixels,showing a first portion of a second image of a second object on thefirst active display area, and showing a second portion of the secondimage of the second object on the third active display area, in whichthe second image of the second object spans continuously across thefirst active display area and the third active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of the second active display area of the seconddisplay panel, the third active display area comprising a plurality ofpixels, showing a first portion of a second image of a second object onthe second active display area, and showing a second portion of thesecond image of the second object on the third active display area, inwhich the second image of the second object spans continuously acrossthe second active display area and the third active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of first active display area of the first displaypanel, the third active display area comprising a plurality of pixels,and showing a third portion of the image of the object on the thirdactive display area, in which the image of the object spans continuouslyacross the third active display area, the first active display area, andthe second active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of the second active display area of the seconddisplay panel, the third active display area comprising a plurality ofpixels, and showing a third portion of the image of the object on thethird active display area, in which the image of the object spanscontinuously across the first active display area, the second activedisplay area, and the third active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of first active display area of the first displaypanel, the third active display area comprising a plurality of pixels,in which a portion of the third active display area is above a portionof the first active display area, and a portion of the second activedisplay area is above another portion of the first active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of first active display area of the first displaypanel, the third active display area comprising a plurality of pixels,in which a portion of the third active display area is below a portionof the first active display area, and a portion of the second activedisplay area is above another portion of the first active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of second active display area of the second displaypanel, the third active display area comprising a plurality of pixels,in which a portion of the third active display area is above a portionof the second active display area, and another portion of the secondactive display area is above a portion of the first active display area.

The method can include positioning a third display panel in which aportion of a third active display area of the third display paneloverlaps a portion of second active display area of the second displaypanel, the third active display area comprising a plurality of pixels,in which a portion of the third active display area is below a portionof the second active display area, and another portion of the secondactive display area is above a portion of the first active display area.

In another general aspect, a method comprises: determining whether asecond display is in proximity to a first display; upon determining thatno second display is in proximity to the first display, showing acontent item and an advertisement on the first display; and upondetecting that the second display is in proximity to the first display,showing at least a portion of the content item on the first display andshowing the advertisement on the second display.

Implementations can include one or more of the following features.Determining whether a second display is in proximity to a first displaycan include determining whether a second display overlaps a firstdisplay.

Showing at least a portion of the content item on the first display caninclude showing the content item across the first and second displays.

The method can include detecting a resolution of the second display, andsending information about the resolution of the second display to an adserver to enable the ad server to provide the advertisement based on theresolution of the second display.

Showing the content item on the first display can include showing thecontent item in a first web browser shown on the first display.

Showing the advertisement on the second display can include showing theadvertisement in a second web browser shown on the second display.

The content item can include a video.

Showing at least a portion of the content item on the first display caninclude showing the content item across the first and second displays.

The method can include continuing to show the advertisement on thesecond display as the content item is being scrolled down to show otherpages.

In another general aspect, a computer-implemented method comprises:receiving a plurality of bids for advertising positions that areassociated with a keyword, the advertising positions comprising a firstadvertising position that is located on a first display and a secondadvertising position that is located on a second display in proximity tothe first display; receiving a query and one or more keywords associatedwith the query; performing an auction based at least in part on thequery, the one or more keywords that are associated with the query, andthe plurality of bids; and based on the bid from the plurality of bidsand on the auction, assigning, by the one or more processors, the firstadvertising position to a first bidder and the second advertisingposition to a second bidder.

Implementations can include one or more of the following features. Thesecond advertising position can be located on a second display thatoverlaps the first display.

The advertising positions can include a third advertising position thatis located on a third display that is in proximity to the seconddisplay.

The third display can overlap the second display.

The advertising positions can include a third advertising position thatis located on a third display that is in proximity to the first display,the second display is on a first side of the first display and the thirddisplay is on a second side of the first display.

The second display can be on a right side of the first display and thethird display can be on a left side of the first display.

The second display can be on a right side of the first display and thethird display can be on a top side of the first display.

The third display can overlap the first display.

In another general aspect, a computer-implemented method comprises:receiving a stored key value from a second display that is in proximityto a first display; determining whether the stored key value is a validkey value; and upon determining that the stored key value is a valid keyvalue, showing a protected content item on at least one of the firstdisplay or the second display.

Implementations can include one or more of the following features. Themethod can include upon detecting that the second display is inproximity to the first display, querying the second display for thestored key value.

The method can include upon detecting that the second display is inproximity to the first display, showing at least a portion of theprotected content item on the first display and showing an advertisementon the second display. Showing a protected content item can includeshowing at least one of a news article, a magazine article, an e-bookarticle, a journal article, a photograph, a drawing, a video, or a blog.

Other aspects include other combinations of the features recited aboveand other features, expressed as methods, apparatus, systems, programproducts, and in other ways. Other features and advantages of thedescription will become apparent from the following description, andfrom the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1-7 are diagrams of extendable display systems.

FIG. 8 is a diagram of a display panel.

FIGS. 9-13 are diagrams of extendable display systems.

FIGS. 14 and 15 are diagrams of mobile phones and removable displaypanels.

FIG. 16 is a cross-sectional diagram of a display.

FIG. 17 is a diagram of a display system that includes two displaypanels.

FIG. 18 is a cross-sectional diagram of a display.

FIG. 19 is a cross-sectional diagram of a portion of the display shownin FIG. 18.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

This description describes an extendable display system that includestwo or more display modules that can be arbitrarily positioned adjacentto each other, a sensor to detect the relative positions of the displaymodules, and a display controller to determine image signals to be sentto each display module such that the two or more display modulesfunction cooperatively as a large unified display.

One of the features of the invention is that a user can convenientlyform a larger display using multiple smaller displays when there is aneed to show larger images, and then conveniently convert back to thesmaller displays for ease of transport or storage when it is no longernecessary to show the larger images. Sensors and display controllers canautomatically determine the relative positions of the display devices(or the relative positions of the active display regions of the displaydevices). When pixel arrangements (e.g., pixel geometric configurationsand pixel pitches) of each individual smaller display and the relativepositions and orientations of the smaller displays are known, thedisplay controller(s) (or graphics controller(s), video controller(s))can determine which portions of a larger image should be displayed oneach of the smaller displays, resulting in the larger image spanningacross the smaller displays and having an effect that is comparable toshowing the larger image on a single unit large display. The large imagecan represent, e.g., a computer desktop, a display screen window, agraphics user interface, a graphics design, a text document, a stillimage, a video, or a combination or two or more of the above.

Another one of the features of the invention is that servers thatprovide image contents can communicate with the display controller(s) toprovide image contents according to the dimensions and resolution of theoverall larger display. If the multiple smaller displays form a largerdisplay that is, e.g., 10 feet wide and 2 feet high, the server computerselects an image that has an aspect ratio closer to 10:2 and sends theselected image to the display controller of the smaller displays. If thelarger display is, e.g., 2 feet wide and 10 feet high, the servercomputer selects an image that has an aspect ratio closer to 2:10 andsends the selected image to the display controller of the smallerdisplays. If the larger display has an overall resolution of about,e.g., 100,000×80,000 pixels, the server selects an image having aresolution approximately 100,000×80,000 pixels or scale an originalimage to produce a modified image that has a resolution approximately100,000×80,000 pixels. If the larger display has an overall resolutionof about, e.g., 800,000×1,600,000 pixels, the server selects an imagehaving a resolution approximately 800,000×1,600,000 pixels or scale anoriginal image to produce a modified image that has a resolutionapproximately 800,000×1,600,000 pixels.

Another one of the features of the invention is that server computersthat provide image contents can combine images captured from multiplecameras to produce images having high resolutions that can be displayedon the larger displays. For example, an array of cameras can be used tocapture images of scenery that is viewed by a person at a location(e.g., New York Times Square, Washington Monument, or Paris EiffelTower). The computer server can selectively combine images from two ormore of the cameras to generate a larger image having a resolutioncompatible with the resolution of the larger display formed by thesmaller displays. For example, suppose an image of the Paris EiffelTower and its surroundings is taken using full frame camera sensors thateach has a resolution of 5760×3840 pixels. An array of 10 by 10 fullframe camera sensors can produce a combined image having a resolution ofabout 57,600×38,400 pixels. If the user forms a larger display having aresolution of 30,000×20,000, the computer server can select images froman array of 6 by 6 cameras to form images having a resolution of34,560×23,040, and either crop or re-scale the images to have theresolution of 30,000×20,000. If all of the images from the 100 sensorsin the array of 10 by 10 full frame camera sensors are used, thecombined image will have a resolution of 57,600×38,400 pixels. If weassume that the smaller displays each has a pixel density of 192 dotsper inch (dpi), the 57,600×38,400 image can be shown on a larger displayhaving dimensions of 300×200 inches or 25×16.67 feet. Such a largedisplay can be placed on, e.g., the wall of a large room or hall.

In some implementations, the computer server can enhance the resolutionof an image by identifying the objects shown in the image, and renderhigh resolution images of the objects based on previously stored imagesof the objects or physical models of the objects. Suppose a single fullframe camera sensor having a resolution of 5760×3840 is used to captureimages of the Paris Eiffel Tower and its surroundings. A user forms alarger display having dimensions of 3×4 feet using smaller displays tosimulate a life-size window. Assuming that the smaller displays each hasa pixel density of 192 dots per inch (dpi), the larger display will havea resolution of 6912×9216. The 5760×3840 resolution image can beup-scaled to 16588×9216 pixels then cropped to 6912×9216 pixels. In someimplementations, the server computer has images of the Eiffel Towertaken from many users from various distances and viewing directions. Thecomputer server can generate a 3D model of the Eiffel Tower usingtechniques similar to those used in the Photosynth software fromMicrosoft, which analyzes images using pattern recognition to generate3D models of objects in the images. By analyzing the 5760×3840resolution image of the Eiffel Tower, the computer server can determinethe position of the camera sensor relative to the Eiffel Tower. Thecomputer server then generates a high resolution 2D image of the EiffelTower based on the 3D model of the Eiffel Tower, taking into account theposition of the camera sensor, the lighting effects (e.g., sunlightdirection and cloud shadows) on the Eiffel Tower, and effects generatedby other objects, such as people, birds, trees, or buildings blockingportions of the Eiffel Tower from view. The higher resolution 2D imageof the Eiffel Tower is inserted into the 6912×9216 image and blended inwith the other portions of the image, and the modified image is sent tothe user.

Example 1

Referring to FIG. 1, in some implementations, an extendable displaysystem 100 includes a first display module 102 and a second displaymodule 104. When the first and second display modules 102, 104 areplaced side-by-side along the x-direction, they can be moved relative toeach other along the y-direction, and the system 100 automaticallyadjusts the image content shown on the display modules 102, 104 based onthe relative positions of the display modules 102, 104 so that the imagecontent extends correctly across the display modules 102, 104.

In the example shown in FIG. 1, the display module 104 is lower than thedisplay module 102 (in the y-direction), but the content (an image of aship) extends correctly across the display modules 102, 104, meaningthat a portion 110 of the image content shown on the display module 102at an edge 114 aligns properly with a portion 112 of the image contentshown on the display module 104 at an edge 116, in which the edges 114and 116 are positioned adjacent to each other. This way, the imagecontent is shown on the display modules 102 and 104 as if the imagecontent is shown on a large unified display.

Referring to FIG. 2, in some implementations, the display module 102includes a sensor 106 positioned at a side 118 of the display module102. The display module 104 includes markings 108 positioned along aside 120 of the display module 104. The side 118 faces the side 120 whenthe display modules 102 and 104 are placed adjacent to each other, suchthat the sensor 106 can detect the markings 108. The markings 108 canbe, e.g., one-dimensional bar codes, two-dimensional bar codes, scalemarks, or other markings. In some implementations, the sensor 106 can bean image sensor that captures images of the markings 108. A dataprocessor processes the image data to determine the position of thedisplay module 104 relative to the display module 102.

Referring to FIG. 3, in some implementations, the display module 102 hasmarkings 122 on a side 124 opposite the side 118, and the display module104 has a sensor 126 on a side 128 opposite the side 120. This allowsadditional modules (e.g., 130, 132) to be positioned adjacent to thedisplay modules 102 and 104, as shown in FIG. 4.

Referring to FIG. 5, a computer 136 may include a data processor, amemory device, a non-volatile memory device (e.g., hard drive or solidstate drive), a display controller, and input devices (e.g., keyboard,mouse, touch input interfaces, voice command interfaces, and/or gesturecommand interfaces). The computer 136 may generate image data andtransmit the image data to the display modules 102, 104 wirelesslythrough wireless links 138, 140, respectively. The display module 102transmits the sensor data from the sensor 106 to the computer 136 toenable the computer 136 to determine the position of the display module104 relative to the display module 102.

Referring to FIG. 6A, in some implementations, when the computer 136intends to display an image 142 that spans both of the display modules102 and 104, the computer 136 can scale the image 142 to have a sizethat is entirely contained within the display regions of the displaymodules 102, 104. The computer 136 splits the image 142 into twoportions 146 and 148, sends the first portion 146 to the first displaymodule 102, and sends the second portion 148 to the second displaymodule 104.

Referring to FIG. 6B, when the user moves the image 142 upwards, aportion 144 of the image 142 moves outside of the display area of thefirst display module 102 and becomes not visible. Referring to FIG. 6C,when the user moves the image 142 downwards, a portion 150 of the image142 moves outside of the display area of the second display module 104and becomes not visible.

Referring to FIG. 6D, in some implementations, when the computer 136intends to display an image 142 that spans both of the display modules102 and 104, the computer 136 can scale the image 142 to have a sizethat utilizes the entirety of the display regions of the display modules102, 104. The computer 136 splits the image 142 into two portions 156and 158, sends the first portion 156 to the first display module 102,and sends the second portion 158 to the second display module 104.

In the example of FIG. 6D, a portion 152 of the image 142 is outside thedisplay region of the first display module 102, and a portion 154 of theimage 142 is outside the display region of the second display module104. The computer 136 determines a first portion of the image 142 thatcan be shown in the display region of the first display module 102 andsends graphic data to the first display module 102 to cause the firstdisplay module to show the first portion of the image 142. The computer136 determines a second portion of the image 142 that can be shown inthe display region of the second display module 104 and sends graphicdata to the second display module 104 to cause the second display module104 to show the second portion of the image 142.

Example 2

Referring to FIG. 7, a display system 160 includes a first display panel162 and a second display panel 164. The first display panel 162 has afirst active display region 166. The second display panel 168 has asecond active display region 168 and a transparent or semi-transparentborder region 170. The transparent or semi-transparent border region 170overlaps the first active display region 166 such that some of thepixels of the first active display region 166 are covered by thetransparent or semi-transparent border region 170.

When the display system 160 shows an image 188 that includes an object180 that spans the first and second active display regions 166 and 168,a first portion 172 of the object 180 is shown by pixels in the firstactive display region 166 not covered by the border region 170, a secondportion 174 of the object 180 is shown by pixels in the first activedisplay region 166 that are covered by the border region 170, and athird portion 176 of the image 180 is shown by pixels in the secondactive display region 168.

The second active display region 168 has a portion 182 that extends overa portion of the frame of the first display panel 162. The seconddisplay panel 164 may be designed to extend the display area of aparticular model of first display panel 162 in which the bezel width ofthe first display panel 162 is known, so the width of the portion 182extending over the first display panel 162 is designed to be the same asthe width of the bezel. This way, the edge of the second active displayregion 168 is aligned with the edge of the first active display region166.

In some implementations, the driver circuits (e.g., column drivers androw drivers) of the second display panel 164 can be placed near bordersor edges of the second active display region 168 that are covered byframe portions 178, 184, and 186. For example, if the transparent orsemi-transparent border region 170 is on the left side of the seconddisplay panel 164, then the row drivers can be positioned near the rightedge 184, and column drivers can be positioned near the upper edge 186and/or the lower edge 178.

In some implementations, the second active display region 168 includes asubstrate and pixel circuits formed on the substrate. The frame portion184 protects the right edge, the frame portion 186 protects a portion ofthe upper edge, and the frame portion 178 protects a portion of thelower edge of the second active display region 168. In someimplementations, to keep the portion 182 thin, the portion 182 is notprotected by a frame portion. In some implementations, the edges of theportion 182 is protected by a thin flexible plastic material that wrapsaround the upper or lower edge of the portion 182.

Referring to FIG. 8, in some implementations, a sensor is provided on abackside of the portion 182 of the second display panel 168. The sensoris configured to sense a parameter that provides information about aposition of the second display panel 168 relative to the position of thefirst display panel 166 and generate a sensor output signal. Forexample, the sensor can include one or more individual photo sensors orimage sensors. In the example of FIG. 8, the sensor includes a firstseries of photo sensors or image sensors 190 and a second series ofphoto sensors or image sensors 192. The photo or image sensors 190 and192 sense light emitted from one or more pixels of the first displaypanel 166 that are covered by the portion 182 of the second displaypanel 164. By using two series of photo sensors or image sensors 190 and192, it is possible to determine the orientation of the second displaypanel 164 relative to the first display panel 162.

Referring to FIG. 9, the first display panel 162 may show a line 200near a right edge of the active display region 166. The line 200 issensed by a photo sensor 202 (of the series of photo sensors 190) and aphoto sensor 204 (of the series of photo sensors 192). The first displaypanel 162 activates each pixel on the line 200 from top to bottom untilthe light from the pixel is sensed by the photo sensor 202. Thisindicates that the sensor 202 is facing the activated pixel. The firstdisplay panel 162 actives each pixel on the line 200 from bottom to topuntil the light from the pixel is sensed by the photo sensor 204. Thisindicates that the sensor 204 is facing the activated pixel.

Because the coordinates of the sensors 202 and 204 on the second displaypanel 164 are known, and the coordinates of the corresponding pixels onthe first display panel 162 are also known, it is possible to accuratelydetermine the relative positions (displacement in the x and ydirections) and orientations of the first and second display panels 162,164. This allows a graphics controller to determine what images to showon the first and second display panels 162, 164 such that the imagesshown on the first and second display panels 162, 164 correctly align atthe border 206 between transparent or semi-transparent region 170 andthe portion 182 of the second active display region 168.

The sensors 202 and 204 can be made of an image sensor having an array(or a series) of photo sensors and an array (or a series) ofmicro-lenses that focus light onto the photo sensors. There may bemultiple rows of micro-lenses in which different rows have differentfocal lengths in order to focus light from the pixels of the firstdisplay panel 162 at different distances. Each of the sensors 202 and204 can be a contact image sensors that includes an array of photosensors and an array of lenses, such as a Selfoc lens array. The photosensors can be formed directly on the back side of the substrate thatsupports the pixel circuits on the front side. The photo sensors canalso be formed on a separate substrate that is bonded to the substratethat supports the pixel circuits.

The back side of the transparent or semi-transparent border region 170can have an anti-reflective coating, or an anti-reflective multi-layercoating to increase transmissivity of light from the pixels of the firstactive display region 166 through the transparent or semi-transparentborder region 170.

Referring to FIG. 10, in some examples, the rows of the first activedisplay region 166 extends at an angle relative to the rows of thesecond active display region 168. Let's assume that a first sensor onthe backside of the region 182 detected a pixel at position A on theline 200 shown on the first active display region 166. The first sensorcorresponds to a pixel on the front side of the active display region168 having coordinates (x12, y12) in the second display coordinatesystem. In the second display coordinate system, the upper left cornerof the second active display region 168 is the origin O2 withcoordinates (0, 0). The pixel at position A on the first active displayregion 166 has coordinates (x11, y11) in the first display coordinatesystem. In the first display coordinate system, the upper left corner ofthe first active display region 166 is the origin O1 with coordinates(0, 0). Here, we assume that the x and y pitches of the first and secondactive display regions 166 and 168 are the same, so that the x and ydimensions of a pixel on the second active display region 168 havingcoordinates (i1, i2) relative to the origin O2, will be the same as thex and y dimensions of a pixel on the first active display region 168having coordinates (i1, i2) relative to the origin O1.

In this example, the pixel (x12, y12) on the second active displayregion 168 overlaps the pixel (x11, y11) on the first active displayregion 166. The coordinates (x12, y12) refer to the coordinates of thepixel on the front side of the active display region 168 in the seconddisplay system, and the coordinates (x11, y11) refer to the coordinatesof the pixel of the first active display region 166 in the first displaysystem.

Assume that a second sensor on the backside of the region 182 detected apixel at position B on the line 200 shown on the first active displayregion 166. The second sensor corresponds to a pixel on the front sideof the active display region 168 having coordinates (x₂₂, y₂₂) in thesecond display coordinate system. The pixel at position B on the firstactive display region 166 has coordinates (x₂₁, y₂₁) in the firstdisplay coordinate system. In this example, because the line 200 is avertical line, x₁₁=x₁₁. The relative angle θ between the first andsecond active display regions 166, 168 can be calculated as follows.

$\begin{matrix}{{{{Tan}(\theta)} = {\left( {{x_{12} - x_{22}}} \right)/\left( {{y_{12} - y_{22}}} \right)}},{{{so}\mspace{14mu} \theta} = {\arctan \left( {\left( {{x_{12} - x_{22}}} \right)/\left( {{y_{12} - y_{22}}} \right)} \right)}},} & (1) \\{{{or}\mspace{14mu} \theta} = {{\arctan \left( \frac{{x_{12} - x_{22}}}{{y_{12} - y_{22}}} \right)}.}} & (2)\end{matrix}$

Assume that the coordinates of the origin O₂ of the second activedisplay region 168 in the first display coordinate system is (Δx, Δy),then Δx and Δy can be calculated as follows.

Δx=x ₁₁ −y ₁₂*sin(θ)−x ₁₂*cos(θ),  (3)

Δy=y ₁₁ −y ₁₂*cos(θ)+x ₁₂*sin(θ).  (4)

If a pixel P1 on the first active display region 166 has coordinates(x₃₁, y₃₁), then the pixel P2 on the second active display region 168that overlaps the pixel P1 will have coordinates (x₃₂, y₃₂) in which

$\begin{matrix}{\mspace{95mu} {x_{32} = {{\left( {x_{31} - {\Delta \; x}} \right)*{\cos (\theta)}} - {\left( {y_{31} - {\Delta \; y}} \right)*{{\sin (\theta)}.}}}}} & (5) \\{y_{32} = {{{x_{32}*{\tan (\theta)}} + {\left( {y_{31} - {\Delta \; y}} \right)/{\cos (\theta)}}} = {{\left( {x_{31} - {\Delta \; x}} \right)*{\sin (\theta)}} - {\left( {y_{31} - {\Delta \; y}} \right)*{\sin (\theta)}*{\tan (\theta)}} + {\frac{y_{31} - {\Delta \; y}}{\cos \; (\theta)}.}}}} & (6)\end{matrix}$

If a pixel P3 on the second active display region 168 has coordinates(x₄₂, y₄₂), then the pixel P4 on the first active display region 166that is covered by the pixel P3 will have coordinates (x₄₁, y₄₁) inwhich

x ₄₁ =x ₄₂/cos(θ)+y ₄₂*sin(θ)−x ₄₂*sin(θ)*tan(θ)+Δx,  (7)

y ₄₁ =y ₄₂*cos(θ)−x ₄₂*sin(θ)+Δy.  (8)

A graphics controller module controls the first and second activedisplay regions 166, 168 such that when the control module detects thatthe second display panel 164 overlaps the first display panel 164 inwhich the first active display region 166 is adjacent to the secondactive display region 168 or overlaps a portion of the second activedisplay region 168, the first and second active display regions 168 showan image that spans a portion of the first active display region 166behind the transparent or semi-transparent border region 170 and aportion of the second active display region 168 adjacent to thetransparent or semi-transparent border region 170.

In some implementations, the positions of the smaller displays relativeto one another can be determined by using a smartphone having a camerathat takes pictures of the smaller displays. The smaller displays maytake turns showing markings on the edges or corners of the displays. Thesmartphone may communicate with the display controller in order todetermine the relative positions of the smaller displays. For example,suppose two displays partially overlap in which the right display (i.e.,the display positioned on the right side) has a left border on top of aleft display (i.e., the display positioned on the left side). The twodisplays take turns showing the rectangular borders of the activedisplay areas. The right display shows a complete rectangular border,whereas the left display shows a partially obscured border. The imagescaptured by the smartphone can be used to determine that the rightdisplay is above the left display. The display controller controls theleft display to show a vertical line starting from the right border,gradually moving toward the left border. Initially, the vertical line isbehind the right display and is not captured by the camera of thesmartphone. When a portion of the vertical line is in the image capturedby the camera, the smartphone informs the video controller, so that thevideo controller can determine which portion of the left display iscovered by the right display. The images captured by the camera can alsobe used to determine the relative angles of the two displays.

The camera can be part of a head-mounted device, such as a head-mountedaugmented reality system. The camera can also be part of a pair ofeyeglasses. For example, the camera can be integrated into a portion ofthe eyeglasses frame. An advantage of using a camera mounted on theeyeglasses frame is that the images captured by the camera are similarto the images seen by the user's eyes. When the displays are calibratedby the camera such that a line spans continuously across the displays inthe images captured by the camera, the images shown on the displays asseen by the user's eyes will align accurately across the displays. Thisis useful when the user is looking at the display panels 162, 164 at anangle that is different from the vertical direction. The portion 182 hasa thickness such that when a first pixel on the top active displayregion (e.g., 168 in FIG. 10) is vertically aligned with a second pixelon the bottom active display region (e.g., 166 in FIG. 10), the firstpixel may not overlap the second pixel when the user views the displaypanels 162, 164 at an angle.

When the camera integrated in the eyeglasses frame is used to calibratethe display panels 162, 164, the image shown on the second display panel164 may be slightly shifted relative to the first display panel 162depending on the user's viewing angle.

For example, FIG. 16 shows a cross-sectional view of the first andsecond active display regions 166, 168, along a boundary 290 between thetransparent or semi-transparent border region 170 and the portion 182 ofthe second active display region 168 (see FIG. 7). The portion 182 ofthe second active display region 168 overlaps a portion of the firstactive display region 166 covered by the border region 170.

The portion of the first active display region 166 includes a layer ofpixel circuits 272, a layer 270 below the layer of pixel circuits 272,and a layer 274 above the layer of pixel circuits 272. The layer 270 caninclude, e.g., a substrate that supports the layer of pixel circuits276. The layer 274 can include, e.g., a protective layer, a color filterlayer, a polarization layer, or a combination of the above layers.Similarly, the portion 182 of the second active display region 168 caninclude a layer of pixel circuits 276, a layer 278 below the layer ofpixel circuits 276, and a layer 280 above the layer of pixel circuits276. The layer 278 can include, e.g., a substrate that supports thelayer of pixel circuits 276. The layer 280 can include, e.g., aprotective layer, a color filter layer, a polarization layer, or acombination of the above layers.

In FIG. 16, the pixels in the layer 272 are immediately to the left ofthe boundary 290 (see FIG. 7), and the pixels in the layer 276 areimmediately to the right of the boundary 290. Consider the situationswhen the user views the pixels in the layers 272 and 276 along viewingdirections that lie on a plane aligned with the boundary 290 andperpendicular to the surface of the active display regions 166, 168.When the user views the displays in a direction perpendicular to thesurface of the active display regions, such as when the user's eye is atposition P1, the pixel 2 in the layer 272 is aligned with the pixel 2 inthe layer 276. In this example, in order for the pixel images shown bythe pixels of the layer 276 to align with the pixel images shown bypixels of the layer 274, the pixels 1-20 of the layer 276 should showpixel images that are aligned with pixels 1-20 of the layer 272. Thus,if a line that is 10 pixels wide extends in the x-direction across theborder 290 at pixels 1 to 10 of layer 272, then at the portion 182 theline should be shown by pixels 1-10 of layer 276.

For example, if the user views the displays in a direction at an anglerelative to the perpendicular direction, such as when the user's eye isat position P2, the pixel 2 in the layer 272 is aligned with the pixel 4in the layer 276. In this example, in order for the pixel images shownby the pixels of the layer 276 to align with the pixel images shown bypixels of the layer 274, the pixels 3-22 of the layer 276 should showpixel images that are aligned with pixels 1-20 of the layer 272. Thus,if a line that is 10 pixels wide extends in the x-direction across theborder 290 at pixels 1 to 10 of layer 272, then at the portion 182 theline should be shown by pixels 3-13 of layer 276.

For example, if the user's eye is at position P3, the pixel 2 in thelayer 272 is aligned with the pixel 7 in the layer 276. In this example,in order for the pixel images shown by the pixels of the layer 276 toalign with the pixel images shown by pixels of the layer 274, the pixels6-25 of the layer 276 should show pixel images that are aligned withpixels 1-20 of the layer 272. Thus, if a line that is 10 pixels wideextends in the x-direction across the border 290 at pixels 1 to 10 oflayer 272, then at the portion 182 the line should be shown by pixels6-15 of layer 276.

For example, if the user's eye is at position P4, the pixel 2 in thelayer 272 is aligned with the pixel 12 in the layer 276. In thisexample, in order for the pixel images shown by the pixels of the layer276 to align with the pixel images shown by pixels of the layer 274, thepixels 11-30 of the layer 276 should show pixel images that are alignedwith pixels 1-20 of the layer 272. Thus, if a line that is 10 pixelswide extends in the x-direction across the border 290 at pixels 1 to 10of layer 272, then at the portion 182 the line should be shown by pixels11-20 of layer 276.

The images captured by the camera of the smartphone or smart eyeglassescan also be used to calibrate the brightness, contrast, and color acrossthe multiple smaller displays so that the multiple displays have thesame or similar brightness, contrast, and/or color. The images capturedby the camera can be used to determine the amount of compensationrequired for the pixels covered by the transparent (or semi-transparent)border of another display. For example, the lower display may increasethe brightness of the pixels covered by the transparent (orsemi-transparent) border of the upper display until the image has auniform brightness across the displays. For example, the lower displaymay adjust the color of the pixels covered by the transparent (orsemi-transparent) border of the upper display until the image has auniform color across the displays.

Referring to FIG. 11, in some implementations, the first display panel162 is treated as the main display, and the graphics controller firstdetermines an image 210 that would cover all of the pixels of both thefirst and second display panels 162, 164. The graphics controllerdetermines the coordinates of the corners of the second display panel164 using the first display coordinate. In the example of FIG. 11, theminimum x coordinate of the image is 0, the maximum x coordinate of theimage is the x coordinate of the point P2, the minimum y coordinate ofthe image is the y coordinate of the point P1, and the maximum ycoordinate of the image is the y coordinate of the point P3, all usingthe first display coordinate.

For example, suppose each of the first and second display panels has aresolution of 1920×1080 pixels. Suppose the origin O2 of the seconddisplay panel 164 overlaps pixel (1820, 20) on the first display panel162, and the angle between the edges of the first and second displaypanels is 5°. Using equations (7) and (8), we can determine that pointP1, corresponding to pixel (1920, 0) in the second display coordinatesystem, corresponds to (3732.69, −147.34) or (3733, −147) in the firstdisplay coordinate system. Point P2, corresponding to pixel (1920, 1080)in the second display coordinate system, corresponds to (3826.82,928.55) or (3827, 929) in the first display coordinate system. Point P3,corresponding to pixel (0, 1080) in the second display coordinatesystem, corresponds to (1914.13, 1095.89) or (1914, 1096). Thecontroller generates an image that spans from (0, −147) on the upperleft corner to (3827, 1096) on the lower right corner.

Let's assume that the color and brightness values of each pixel for theimage using the first display coordinate system is known. The firstactive display region 166 shows the portion of the image 210 that spansfrom (0, 0) on the upper left to (1920, 1080) on the lower right. Thecolor and brightness of each pixel in the second active display region168 can be determined as follows.

For each pixel S1 in the second active display region 164, the graphicscontroller determines the coordinates in the first display coordinatesystem using equations (7) and (8), looks up the color and brightnessvalues for that pixel in the image 210, and assigns the color andbrightness values to the pixel S1. Using equations (7) and (8), thecoordinates may have decimal points. In some examples, we can round offthe decimal points of the coordinates so that the pixel S1 maps to apixel on the image 210. In some examples, if the pixel S1 maps to apoint between centers of pixels on the image 210, the color andbrightness of the pixel S1 can be determined based on a weighted averageof the color and brightness values, respectively, of the pixel where thepoint falls on the pixels adjacent to the point.

Referring to FIG. 12, when there are three display panels 162, 164, and220, the graphics controller can determine the coordinates of each pixelon the third display panel 220 in the second display system, and thendetermine the coordinates of the pixel in the first display system. Thegraphics controller determines an image 222 that covers all threedisplay panels. The color and brightness of each pixel in the firstdisplay coordinate system are known. The coordinates of each pixel inthe second active display region in the first display coordinate systemare calculated, and the color and brightness can be determined accordingto the method described above. Similarly, the coordinates of each pixelin the third active display region in the first display coordinatesystem are calculated, and the color and brightness can be determinedaccording to the method described above.

Referring to FIG. 13, when there are four display panels 162, 164, 220,and 230 that overlap at borders, the same method can be used todetermine the color and brightness values of each pixels of the displaypanels 162, 164, 220, and 230. Additional display panels can be added tofurther expand the overall display area.

If the image sensors at the backside of the display panels are used todetermine the relative positions and orientations of the display panels,then the display panels need to partially overlap to enable the backsidesensors to sense the light from the lower display panels. If an externalcamera is used to calibrate the alignment of the displays, then theactive areas of the display panels do not need to overlap. For example,FIG. 17 shows a first active display region 300 and a second activedisplay region 302 that collaboratively show an image of a circle 304that extends across the first and second active display regions 300,302. When the position of the second active display region 302 relativeto the first active display region 300 changes, based on the feedbacksignals from the camera, the graphics controller dynamically adjusts theimage shown on the second active display region 302 such that the circle304 continues to be accurately shown across the first and second activedisplay regions 300, 302.

In some implementations, each display panel has transparent orsemi-transparent borders on all edges, such as the top, bottom, left,and right edges. The transparent or semi-transparent borders are thin,whereas the middle portion of the display panel is thicker and housesthe circuitry for driving the displays. FIG. 18 shows an exemplarydisplay device 310 that includes a module 312 and a thin pixel layer314. The module 312 includes circuitry for driving the pixels, battery,controller, and memory, etc. The thin pixel layer 314 has portions,e.g., 316, 318 that extend beyond the edges of the module 312, so thatthe portions 316 and 318 can overlap the active display regions of otherdisplays. In some implementations, the thin pixel layer 314 is protectedby a transparent or semi-transparent film 320. Referring to FIG. 19, insome implementations, the transparent or semi-transparent film 320 maybe formed by an upper film 324 and a lower film 322 that are laminatedor bonded together.

In some implementations, the display panels are OLED display panels thatdo not require backlight and thus can be made thin.

In some implementations, the pixel pitch (distance between pixels) fordifferent display panels may be different. Equations (7) and (8) can bemodified by using a scaling factor to take into account of thedifferences in pixel pitch.

An advantage of the display system described in this document is thatthe display panels do not have to be perfectly aligned, the system candetermine the relative positions of the display panels and adjust thecontents shown on the display panels accordingly. This is in contrast tothe conventional display walls in which the content sent to each displaypanel is fixed, and the user has to ensure that the display panels areperfectly aligned in order for the image portions to be alignedproperly. The display system described here dynamically adjustsdisplayed contents based on relative positions of the display panels.

An advantage of the display system described here is that the user caneasily add more display panels to increase the display screen area, orremove display panels when the larger screen area is not needed. Forexample, referring to FIG. 14, a mobile phone 240 has an active displayarea 244. For ease of portability, the mobile phone 240 has a smallsize, so the active display area 244 necessarily has a small size. Whenthe user sits down in front of a desk, the user may want to view contenton a larger screen. The user can use a display panel 242 in which anactive display area 246 has a portion 250 that either aligns with theedge of the active display area 244 or overlaps a portion of the activedisplay area 244. A transparent or semi-transparent border region 248overlaps a portion of the active display area 244. The active displayarea 244 and the active display area 246 effectively form a largerdisplay that can show images that continuously span the active displayareas 244 and 246.

In some examples, the display panel 242 displays images but is notresponsive to touch inputs. This allows the display panel 242 to be madecheaper, thinner, and lighter. The user provides touch commands on theactive display area 244 of the mobile phone 240. In some examples, thedisplay panel 242 is a touch display panel that can accept touch inputs.The display panel 242 can also be made to be sensitive to differentlevels of pen pressure input.

An active display area does not necessarily have to be rectangular inshape. For example, referring to FIG. 15, a display panel 260 has aU-shaped active display area 262 that overlaps portions of, or alignswith, the three edges of the active display area 244 of the mobile phone240. The dashed lines 264 show the contours of the mobile phone 240.

In some implementations, the second display panel can be used to showsponsored content or advertisements while the first display panel showthe main article without sponsored content or with reduced sponsoredcontent. An advertisement is sometimes referred to as an “ad.” Thesponsored content can promote, e.g., consumer products or businessservices. The sponsored content can be associated with, e.g., people orideas. The sponsored content can include, e.g., text, articles, blogs,logos, graphic images, photographs, or videos.

Because the second display panel is in the proximity of the firstdisplay panel, the reader of the main article will still see thesponsored content, but will be less distracted by the sponsored contentcompared to a conventional method of showing the ads embedded in thetext of the main article, or showing the ads next to the main articlesuch that only a small portion of the main article can be read at a timebecause a big portion of the screen space is used by the ads. The systemdetermines whether the second display is in proximity to the firstdisplay. If the system determines there is no second display inproximity to the first display, the system shows a content item, such asan article, and an advertisement on the first display. If the systemdetermines that the second display is in proximity to the first display,such as overlapping the first display, the system shows at least aportion of the content item (e.g., the article) on the first display andshows the advertisement on the second display.

If the second display overlaps the first display, the content item canbe shown across the first and second displays, and the ad can be shownon the second display. The system can detect a resolution of the seconddisplay and send information about the resolution of the second displayto an ad server to enable the ad server to provide the advertisementbased on the resolution of the second display. In some examples, theuser may use a first web browser window to access article from theInternet. Upon determining that the second display is in proximity ofthe first display, the system opens a second web browser window on thesecond display to show the advertisement. The content item can include avideo. The user plays the video, which the system shows on the firstdisplay, and the system shows the advertisement on the second display.The content item may be a long article that is several pages long, andthe user needs to scroll down to see other portions of the article. Thesystem can continue to show the advertisement on the second display asthe content item is being scrolled down to show other pages on the firstdisplay.

In some implementations, advertisers can bid for ad slots positioned onthe same display as the main content or on another display adjacent tothe display on which the main content is shown. For example, a magazineweb site can be configured such that if the user only uses one or moreconventional displays, the main content and the advertisements are shownon the one or more conventional displays. If the user has a seconddisplay that overlaps a first display, or has a second display that hasa particular key value or code, the web site can be configured to showthe main content on the first display and the advertisement on thesecond display. By moving the advertisement to the second display, theuser is not distracted by the ads while reading the main content, butcan still see the ad and click on the ad if interested. The advertiserknows that the ad is being viewed by the user because the second displayoverlaps the first display or is in a vicinity of the first display.

When the ad is shown adjacent to the main content on the first display,the ad is typically smaller so that it doesn't block all of the maincontent. When the ad is shown on the second display, the ad can be aslarge as the second active display area. When the user scrolls down toread other pages of the main content, the second display can continue toshow the ad. When the main content includes video, the second displaycan show ads that are relevant to the content of the video withoutinterrupting the video. The user can pause the video and click on the adif interested.

Because the ads shown on the second display can be larger, can stay onthe display for a longer period of time, the likelihood of the ad beingclicked on or otherwise acted upon by the user is higher than if aconvention display is used. The magazine can charge more for the ad slotpositioned on the second display. In some implementations, a systemrunning an ad auction receives a plurality of bids for advertisingpositions that are associated with a keyword, in which the advertisingpositions include a first advertising position that is located on afirst display and a second advertising position that is located on asecond display in proximity to the first display. The system receives aquery and one or more keywords associated with the query. The systemperforms an auction based at least in part on the query, the one or morekeywords that are associated with the query, and the plurality of bids.Based on the plurality of bids and the auction, the system assigns thefirst advertising position to a first bidder and the second advertisingposition to a second bidder.

In some examples, the second advertising position can be located on asecond display that overlaps the first display. The advertisingpositions can include a third advertising position that is located on athird display that is in proximity to the second display. The thirddisplay can overlap the second display. The advertising positions caninclude a third advertising position that is located on a third displaythat is in proximity to the first display, in which the second displayis on a first side of the first display and the third display is on asecond side of the first display. In some examples, the second displaycan be on a right side of the first display and the third display can beon a left side of the first display. In some examples, the seconddisplay can be on a right side of the first display and the thirddisplay can be on a top side of the first display. The third display canoverlap the first display.

In some implementations, a magazine company can sell the second displaythat overlaps the first display, in which the second display has aunique key value stored in the display. When the user positions thesecond display to overlap the first display, the user can view contenton the web site of the magazine company either free of ads or have theads positioned on the second display. Upon visiting the magazine website, the web server communicates with the user computer to determinewhether there is a second display. Upon determining that there is asecond display, the web server determines whether the second display hasa key value that is associated with an account of a subscriber of themagazine. If the key value is associated with an authorized subscriber,the web server allows the user to view the content either free of ads orhave the ads positioned on the second display. If the key value is notassociated with an authorized subscriber, the second display functionsas an extension of the first display. When the user views content onother web sites, the second display functions as an extension of thefirst display.

In some examples, a content provider can provide images or video havinga resolution that is compatible with the larger display formed by thecombination of smaller displays. For example, the content provider mayhave a server computer having a storage device that stores images withdifferent content. The server may have several versions of each imagewith different resolution. For example, for each image, the server mayhave versions of each image with one or more of resolutions 640×480,800×640, 1024×768, 1280×1024, 1600×1200, 2560×1600, 3840×2160,5120×2880, and 7680×4320 pixels. When a user's computer communicateswith the server computer to access an image, the user's computerprovides information about the resolution of the larger display, and theserver computer chooses a version of the image that has a resolutionthat matches the resolution of the larger display. The server computersends the version of the image to the user's computer, and the user'scomputer shows the image on the larger display. The same principleapplies to providing videos from the server computer to the usercomputer.

In some examples, the larger display may have a resolution that does notmatch the resolution of any version of the images stored at the servercomputer. The server computer can select a version of the image having aresolution that is slightly higher or lower than the resolution of thelarger display. The server computer sends the version of the image tothe user's computer, and the user's computer resizes the image to matchthe resolution of the larger display. The same principle applies toproviding videos to users. The resizing of the images or videos can alsobe performed at the server computer.

When the larger display has an irregular shape, the server computer can(i) provide a version of the image having a horizontal resolution thatmatches, is slightly larger than, or is slightly smaller than theoverall horizontal resolution of the larger display, (ii) provide aversion of the image having a vertical resolution that matches, isslightly larger than, or slightly smaller than, the overall verticalresolution of the larger display, or (iii) provide a version of theimage having horizontal and vertical resolutions that match, are bothslightly larger than, or both slightly smaller than, the overallhorizontal and vertical resolutions, respectively, of the largerdisplay. The server computer sends the version of the image to theuser's computer, and the user's computer shows the image on the largerdisplay, or resizes the image if necessary to match the resolution ofthe larger display.

In some examples, the server computer may generate a version of theimage in which the image has a resolution that is determined based onthe resolution of the larger display connected to the user's computer.For example, the user's larger display may have the size of a window,and the server computer may provide images that simulate scenes that areseen through the window. The server computer may provide images thatrepresent a scene as seen through an apartment window in, e.g., Bostonor Paris. For example, a first user living in an apartment in Paris mayhave a high definition digital camera (having video capabilities)installed outside the window of the apartment, and stream the video fromthe camera to the server computer. The server computer may allow otherusers to subscribe to the video feed.

When a second user in Boston subscribes to the video feed, the servercomputer queries the second user's computer to obtain information aboutthe resolution of the larger display of the second user. The servercomputer adjusts the video resolution (e.g., using interpolation,extrapolation, or other image processing methods) based on theresolution of the larger display associated with the second user, andsends the video to the second user's computer. The second user'scomputer shows the video on the larger display having the size of awindow, so the second user can see what the first user sees outside thewindow of the apartment in Paris. In some examples, the first user canuse multiple cameras to capture videos of the scene outside the Parisapartment window from different angles. The server computer combines thevideos from the multiple cameras to form a single video having a higherresolution. The server computer then provides the higher resolution tothe second user.

In some examples, audio is provided in combination with the video. Inthe example above, the first user may use a microphone to capture thesounds outside the Paris apartment window. Users who subscribe to theParis apartment audio/video feed can see and hear the scenes and soundsof Paris.

The server computer may provide a platform to allow users to uploadvideos or stream live video. Users can upload or live stream video fromdifferent cities or scenic places. These videos have high resolutions,such as having thousands of pixels in the horizontal and/or verticaldirection, so that when the images are shown on the larger display ofthe subscribers, the images represent realistic renderings of the scenesthat the subscribers would see from actual windows.

In some examples, the first user uses a wide-angle camera, or multiplecameras pointed at different directions, to capture one or more videosof the scene outside of the Paris apartment window. One or moredirectional or omnidirectional microphones can be used to capture thesound outside the Paris apartment window. The second user (e.g., someoneliving in Boston) subscribes to the Paris video feed. The second userhas a larger display formed by a combination of overlapping smallerdisplays, in which the larger display has the size of a window and mayeven be configured to look like a physical window.

For example, the larger display may be surrounded by a window frame. A3D camera may be used to capture images of the second user, and softwaremay be used to recognize the user's eyes in the captured images anddetermine the location of the user's eyes relative to the largerdisplay. The second user's computer sends information about theresolution of the larger display, and the position of the second user'seyes relative to the second display to the server computer. The servercomputer generates a second video based on the video(s) provided by thefirst user in Paris, in which the second video takes into account of theposition of the second user's eyes relative to the larger display. Thesecond video represents what the second user would see if the seconduser were in the Paris apartment and the position of the second user'seyes relative to the window in the Paris apartment were the same as theposition of the second user's eyes relative to the larger display inBoston. As the second user moves around in his/her apartment in Boston,the video of Paris shown on the larger display in the Boston apartmentalso changes. The server computer generates in real time videos of Parisbased on the positions of the second user's eyes relative to the largerdisplay in the Boston apartment. The larger display becomes a window toa different world.

The smaller displays can be 3D displays that show 3D images. The smallerdisplays form a larger display that shows a larger 3D image.

For example, the server computer can generate images and sounds that onewould see and hear if he/she were living in a space colony on Mars. Thelarger display formed by multiple smaller displays can have a highresolution and show realistic images of scenes on Mars.

For example, the server computer can generate images and sounds that onewould see and hear if he/she were living on Earth. This may be usefulfor people who live in a space colony on Mars. The larger display formedby multiple smaller displays can have a high resolution and showrealistic images of scenes on Earth, so that people living on Mars canfeel as if they were living on Earth.

For example, a larger display formed by multiple smaller displays can beinstalled in an inside cabin of a cruise ship. Camera can be installedon the outside of the cruise ship to capture images or videos of thescenes around the cruise ship. The larger display shows images or videosof the scenes outside of the cruise ship, so that the people in thecabin feel as if they were looking through a physical window.

For example, a 3D camera may be used to capture images outside of thecruise ship, and an eye-tracking device/software may be used todetermine the location of the user's eyes relative to the largerdisplay. The computer in the cabin sends information about theresolution of the larger display, and the position of the user's eyesrelative to the larger display to the server computer of the cruiseship. The server computer generates a second video based on the video(s)provided by the cameras installed on the outside of the cruise ship, inwhich the second video takes into account of the position of the user'seyes relative to the larger display. The second video represents whatthe user would see if the user were in a cabin with window or balconyand the position of the user's eyes relative to the window or balconywere the same as the position of the user's eyes relative to the largerdisplay. As the user moves around the cabin, the video of the outsidescenes shown on the larger display in the cabin also changes. The servercomputer generates in real time videos of scenes outside the cruise shipbased on the positions of the user's eyes relative to the larger displayin the cabin. The larger display makes the inside cabin feels more likea cabin with a window or a balcony. In some implementations, the smallerdisplays can be 3D displays that show 3D images. The smaller displayscan form a larger display that shows a larger 3D image of the sceneoutside of the cruise ship.

The server computer can generate images and sounds that one would seeand hear if he/she were living in an underwater habitat in a tropicocean. The larger display can show realistic images of underwater scenesof, e.g., whales, sharks, giant octopuses, sea turtles, and colorfulfish swimming by.

The larger displays can be installed in simulators, such as flightsimulators, and show images that simulate what one would see when flyingan airplane. The larger displays can be installed in race car simulatorsand show images that simulate what one would see when driving a racecar. The larger displays can be installed in submarine simulators andshow images that simulate what one would see when diving in the ocean.The larger displays can be installed in space ship simulators and showimages that simulate what one would see when flying in outer space or ondistant moons and planets.

By forming a larger display using a combination of smaller displays, thelarger display can show life-size images that simulate what one wouldsee in real life, allowing simulations to be more realistic than viewingthe images through smaller screens.

While it may be possible to manufacture a large display using a singlesubstrate, such a large display is expensive because of the difficultyof fabricating a perfect display without any defective pixel. The largedisplay made of a single substrate may be difficult to move around orput to storage. By contrast, using a larger display formed by acombination of smaller displays, e.g., overlapping smaller displays, thelarger display can be disassembled and moved around easily. Storage ofthe smaller displays is also much easier compared to storing the largedisplay made of a single substrate.

Using conventional methods, consumers can order displays havingresolutions according to industry standards, such as 640×480 (VGAdisplay), 800×640 (SVGA display), 1024×768 (xGA display), 1280×1024(SxGA display), 1600×1200 (UxGA display), 2560×1600 (WQxGA display),3840×2160 (4K display), 5120×2880 (5K display), and 7680×4320 (8K UltraHigh Definition Display). The consumer can order displays havingparticular shapes (usually rectangle) defined by the manufactures.

In some implementations, by forming a larger display using a combinationof smaller displays, e.g., overlapping smaller displays, a custom-madelarger display can have an arbitrary pixel resolution as specified by auser. For example, a display manufacturing can manufacture displayshaving resolutions of 640×480, 800×640, 1024×768, 1280×1024, 1600×1200,2560×1600, 3840×2160, 5120×2880, and 7680×4320 pixels. If a user ordersa larger display having a resolution of 2000×1600, the manufacturing canoverlap four 1600×1200 displays to form a larger display having aresolution of 2000×1600. If the user orders a larger display of aspecific size, the manufacturing can overlap multiple displays toproduce a display having the requested size. For example, themanufacturer may fabricate a 60-inch (diagonal size) display having asize of 38.4×21.6 inches. If the user orders a larger display having asize of 60 by 60 inches, the manufacturer can overlap six of the 60-inchdisplays (two displays in the horizontal direction and three displays inthe vertical direction) form a larger display having dimensions of 60 by60 inches.

A large number of smaller displays can in combination form a largerdisplay of a high resolution. For example, tens, hundreds, thousands, ormillions of smaller displays can in combination form a larger displayhaving a resolution of thousands, millions, or billions of pixels. Thelarge display can show still images or video in which the refresh ratedepends on the bandwidth of data transmission between the computer andthe smaller displays. Thus, for example, the walls, floors, and ceilingsof a room can be completely covered by smaller displays that incombination form a larger display that can show images that extendcontinuously across the smaller displays as if shown on a single unitlarge display that covers the entire room. The large display can showimages of other locations or worlds. This is useful to provide anexperience to the user similar to virtual reality, without requiring theuser to wear a head-mount display.

The façade of a building may be covered by tiles, in which each tile isa small display. When the builder installs the tile displays on thebuilding walls, the builder does not need to keep track of the positionsof the tiles. Sensors can automatically determine the relative positionsof the tile displays, and the display controller can determine whatimage portion to shown on each tile display so that a large image canspan continuously across the tile displays.

A display manufacturer may pre-fabricate smaller displays having, e.g.,rectangular, triangular, circular, and oval shapes, and then overlap thesmaller displays to form a larger display having an arbitrary shape asspecified by a user.

The smaller display can be configured such that the backside of thetransparent or semi-transparent border is made of a material has arefractive index that is the same or similar to the refractive index ofthe material of the top covering of the active display area. A liquidhaving a refractive index that matches the refractive index of thebackside of the transparent or semi-transparent border of the upperdisplay and the refractive index of the material of the top covering ofthe active display area of the lower display can be applied between thebackside of the transparent or semi-transparent border of the upperdisplay and the top covering of the active display area of the lowerdisplay. This may reduce the amount of light reflected between the backsurface the transparent or semi-transparent border of the upper displayand the top surface of the active display area of the lower display.

For custom-made displays, a large transparent or semi-transparent coverhaving a size that spans the entire larger display can cover theoverlapping smaller displays. An index matching liquid can be appliedbetween the top surface of the smaller displays and the largetransparent or semi-transparent cover to enhance light transmission fromthe smaller displays through the large cover. A frame can be applied tothe border of the larger display so that the larger display has theappearance of a single large display.

In some implementations, a first display can have a sensor at a borderthat can detect that a second display is about to overlap the border ofthe first display. The sensor can be, e.g., a 2D image sensor or a 3Dimage sensor. As the second display approaches the image sensor, thedisplay controller can estimate the amount of overlap between the firstand second displays based on the images captured by the image sensor.The estimated overlap can be used to initialize the process foraccurately determining the overlap between the displays. For example, ifthe display controller estimates that 200 columns of pixels on the rightside of the first display will be covered, then the display controllercan scan a vertical line starting from the 150-th column from the rightborder, instead of from the 1st column from the right border. Thisallows the display controller to accurately determine the amount ofoverlap in a shorter amount of time, reducing the amount of time thatthe user has to wait before images can be properly displayed across theoverlapping displays.

A larger display can be formed by overlapping smaller displays havingdifferent display characteristics. For example, a first display may havea faster refresh rate than a second display. When a computer shows videocontent on the two displays, the computer may take into account thedifferent display characteristics of the two displays. For example,suppose two displays overlap, and the left display has a faster refreshrate and is more suitable for showing video. When the user launches awindow to view a video, if the window can fit within the left display,the computer may initially position the window showing the video on theleft display. If the window is larger than the left display but smallerthan the larger display, the computer may initially position the windowshowing the video to cover the entire left display and a portion of theright display so as to utilize the left display as much as possible.

In some implementations, a larger display is formed by overlapping afirst display that is a liquid crystal display and a second display thatis an E-ink display. When the user launches a video program, thecomputer may initially show the video program on the first display. Whenthe user launches a word processing program, the computer may initiallyshow the word processing program on the second display.

A computer may show additional content as more displays are added toform a larger display. For example, suppose a teacher shows a historytimeline using several displays. The teacher uses a computer to show thetimeline of events from the year 1900 to the year 1945 on a firstdisplay. The teacher overlaps a second display on the right side of thefirst display. The computer shows a timeline of events from the year1945 to the year 2000 on the second display. The teacher overlaps athird display on the right side of the second display. The computershows a timeline of events from the year 2000 to the present day on thethird display. For example, the teacher may add a fourth display on thetop or bottom side of the second display to provide an expanded view ofthe events that happened from the year 1945 to the year 2000. Theteacher may add a fifth display to the top or bottom side of the thirddisplay to provide an expanded view of the events that happened from theyear 2000 to the present day. The teacher may also move the fourthdisplay to the top or bottom side of the third display to provide theexpanded view of the events that happened from the year 2000 to thepresent day. The overlapping displays allow content to be dynamicallypresented in a convenient manner.

The overlapping displays can provide a platform for multiple users tointeract. For example, a first user and a second user can play the gameof pong by controlling paddles shown on a first display. For example, asecond display may overlap a right border of the first display, and athird user and a fourth user can control paddles shown on the seconddisplay. A ball can move between the first and second displays, allowingthe four users to play the game of pong together. For example, a thirddisplay may overlap a right border of the second display, and a fifthuser and a sixth user can control paddles shown on the third display.The ball can move among the first, second, and third displays, allowingthe six users to play the game of pong together. Multiple balls can beused simultaneously to increase the complexity of the game.

A server computer may have a collection of images or video havingdifferent sizes, some having a width greater than the height, while somehaving a height greater than the width. A user may subscribe to aservice for showing images or video on a large display withoutexplicitly specifying which image to show. For example, the user mayindicate a preference for showing images in mountainous scenes. Supposethe user's display has a resolution of 6000 by 1000 pixels. The servercomputer may have images of majestic mountains taken by professionalphotographers, some of the images are panoramic images havingresolutions of 5000×1200 pixels, and some images have resolutions of2000×1200 pixels. Based on the user's display resolution, the servercomputer determines that the images having resolutions of 5000×1200pixels are more suitable for display on the user's display, and sendsthose images to the user.

As another example, the user may have a display that has a resolution of1000 (horizontal) by 8000 (vertical) pixels. The server computer mayhave photos and images of art works, some having resolutions of1000×2000 pixels, and some having resolutions of 1000×6000 pixels. Basedon the user's display resolution, the server computer determines thatthe photos or images having resolutions of 1000×6000 pixels are moresuitable for display on the user's display, and sends those photos orimages to the user.

For example, the user may be the owner of a coffee shop that has a largedisplay hung on a wall. The coffee shop owner subscribes to an imagingservice that provides images to the large display. The images may changeperiodically, such as once every 10 minutes, once every hour, once perday, or once per week. The large display may show a collage of images,and some portions of the large display may show images that are updatedmore frequently than other portions of the display. The imaging serviceprovider has a server computer that has access to a collection of imageshaving various resolutions. The server computer first identifies asubset of images based on the coffee shop owner's preference, thenselects images from among the subset based on the resolution and/or sizeof the large display.

The coffee shop owner may own several coffee shops in the country oraround the world. Different coffee shops may have large displays ofdifferent sizes and/or shapes. The server computer may provide differentimages to the displays installed at various coffee shops based onvarious criteria, including the shapes and sizes of the displays and thelocations of the coffee shops. For example, the server computer mayprovide images that are biased toward Japanese themes to coffee shopslocated in Japan, and provide images that are biased toward Italianthemes to coffee shops located in Italy. The images may be selectedbased on, e.g., local weather and local holidays. The shop manager ofeach coffee shop may reconfigure the display(s) from time to time. Forexample, nine displays may be positioned side-by-side horizontally in a9 by 1 matrix to form a wide panoramic display for a few months, thenre-positioned in a 3 by 3 matrix for a few months. When theconfiguration of the large display changes, the information about theresolution of the large display is provided to the server computer, andthe server computer provides images that are compatible with theresolution of the large display.

In some of the examples above, a server computer provides images to alarger display formed by overlapping smaller displays. The sameprinciples for providing images to the larger display can also beapplied to examples in which the larger display is formed by smallerdisplays that do not overlap, or formed by smaller displays in whichsome smaller displays overlap other displays and some smaller displaysdo not overlap other displays. One of the features of this invention isthat one or more sensors are provided to detect the relative positionsof the smaller displays so that a large image can be properly displayedacross several smaller displays, regardless of whether the smallerdisplays overlap other displays or not. The sensors can be mounted onthe displays (e.g., on the backside of the displays), or be external tothe displays (e.g., camera on smart phones or smart eyeglasses). Theuser can move the positions of the smaller displays relative to otherdisplays and the images shown on each individual smaller display areadjusted automatically so that a larger image is properly shown acrossthe smaller displays.

When the smaller displays do not overlap or have gaps between the activedisplay areas, the video controller determines the appropriate image toshow on each smaller display based on the bezel sizes of the displaysand the relative positions of the displays. For example, suppose thereis a gap of x millimeters between the active areas of a first displayand a second display. A large image can be shown across the active areasof the first and second displays taking into account of the x-millimetergap. For example, suppose two displays are configured as a largerdisplay, and each smaller display has a horizontal dimension of 20inches. Suppose the two displays are used to show a life size pole thatis 60 inches long and positioned horizontally. Suppose the two displaysare positioned side by side horizontally. If the active display area ofthe right display overlaps the active display area of the left displayby 1 inch, then the combination of the left and right displays show 19inches of the life size pole. If there is a 0.5 inch gap between theactive display areas of the left and right displays, then thecombination of the left and right displays show 40.5 inches of the lifesize pole, in which the left display shows the first 20 inches of thepole, and the right display shows the portion of the pole from 20.5 inchto 40.5 inch. If there is a 3-inch gap between the active display areasof the left and right displays, then the combination of the left andright displays shows 43 inches of the life size pole, in which the leftdisplay shows the first 20 inches of the pole, and the right displayshows the portion of the pole from 23 inch to 43 inch.

In the example above, the user can choose the left display to be thestationary display so that when there is a change in the relativeposition or orientation of the left and right displays, the image shownon the left display remains the same and the image shown on the rightdisplay is modified. The user can also choose the right display to bethe stationary display so that when there is a change in the relativeposition or orientation of the left and right displays, the image shownon the right display remains the same and the image shown on the leftdisplay is modified. In some examples, the user can choose a referencepoint that is outside of the left and right displays, so that when thereis a change in the position or orientation of the left or right displayrelative to the reference point, the image shown on the left or rightdisplay is modified accordingly.

A display can be designed such that the back side of the display ispopulated with sensors, such as image sensors. The sensors can be formedon the back side of the substrate supporting the pixels of the activedisplay area on the front side. Conductive traces can be formed in viasor holes passing the substrate so that circuitry on the front side ofthe substrate can communicate with circuitry on the back side of thesubstrate. The sensors can also be formed on a separate substrate thatis bonded to the substrate supporting the pixels of the active displayarea. Conductive traces can be formed in vias or holes passing thesubstrate so that circuitry on the front side of the substrate cancommunicate with circuitry on the back side of the substrate. When thedisplay is placed on a surface, such as the surface of a desk or a wall,the sensors can detect the patterns on the surface. The front sideactive display area of the display shows the patterns detected by thebackside sensors, allowing the display to blend in with the surrounding.This allows the display to camouflage itself.

The back side of the display can also have light emitting devices, suchas light emitting diodes. The light emitting devices illuminate thesurface that is covered by the display, and the sensors detect thepatterns on the illuminated surface. The active display area on thefront side shows the patterns detected by the sensors.

One application of such a display is to hide another object, such as apower cord. For example, a television may be hung on a wall. A hole maybe drilled into the wall to allow a power cord from the television to beconnected to a power line inside the wall. If the user does not wish todrill a hole in the wall, and runs the power cord along the wall to apower socket, a narrow strip of display can cover the power cord andshow patterns that match the wall patterns. The sensors on the back sideof the narrow strip of display may sense the patterns on the wall andthe power cord. The user can configure the display to show only thepatterns on the wall and not the pattern of the power cord, e.g., bycopying the patterns on the wall to cover the pattern of the power cord,or replace the pattern of the power cord with simulated wall patternsthat are generated based on the wall patterns sensed by some of thesensors.

A power cord may be configured such that the front side of the powercord includes an active display area, and the back side of the powercord includes sensors. The active display area shows the patternsdetected by the sensors in order to camouflage the power cord. The backside of the power cord may also have light emitting devices toilluminate the surface covered by the power cord. The active displayarea, the sensors, and the light emitting devices may draw power fromthe power cord or from a power converter that draws power from the powercord.

For example, a display having transparent (or semi-transparent) borderscan be used to camouflage an undesired pattern on a wall (e.g., a holein the wall caused by removing a fixture or an ugly electric panel).Lighting devices on the back side of the display illuminate the surfaceof the wall, sensors on the back side of the display detect patterns onthe surface of the wall (including desired and undesired patterns). Thedetected patterns are shown on the active display area on the front sideof the display. Circuitry on the front side of the display communicateswith circuitry on the back side of the display though signal lines thatpass through the substrate supporting the pixels of the active displayarea. The user selects the undesired patterns to be camouflaged, andselects the desired patterns used to overwrite the undesired patterns.The undesired patterns are replaced by the desired patterns on thedisplay. The display may interact with a computer or smartphonewirelessly to enable a user to control what patterns are shown on thedisplay. A graphics software may process the copied patterns so thatthey blend in with the existing patterns.

A second display having one or more transparent (or semi-transparent)borders can be used to dynamically increase the active display area of afirst display. For example, a user of a 24-inch display having 1920×1200resolution may need to view two text documents side by side. The usermay determine that when the display shows the two documentsside-by-side, the text is too small to be viewed comfortably. The usermay decide that enlarging the first document to have a width that isabout 66% of the horizontal screen area results in the most comfortabletext size. The remaining 34% of the horizontal screen area is too smallto show the second document comfortably. By overlapping a second displayhaving a transparent (or semi-transparent) border at the right side thefirst display, the effective active display area is extended on theright side of the first display. Assuming the second active display areahas a horizontal dimension that is approximately 35% of the horizontaldimension of the first display, and the overlap between the first andsecond active display areas is about 3% of the horizontal dimension ofthe first display, the second display adds about 32% display area in thehorizontal direction. The second document can be shown across the firstand second displays and have a width approximately equal to 66% of thehorizontal dimension of the first display. This way, both documents canbe viewed side-by-side and the user can read the text of both documentscomfortably. After the user finishes viewing the two documents, the usermay decide that the 24-inch display is large enough to perform othertasks, and remove the second display.

In some situations, the user may wish to view more lines of text of adocument at the same time. For example, when a document is shown on afirst display with a text size that is comfortable to read, only 20lines of text can be shown on the display because some of the verticalspace is occupied with the menus and status bars of the word processingprogram. The user may wish to view 30 lines of text together. The usercan overlap a second display having one or more transparent (orsemi-transparent) borders on the top or bottom side of the first displayso that the document can span vertically across the first and seconddisplays. The width of the second display does not have to match thewidth of the first display. For example, the second display may have awidth and a height that are 66% and 50% of the width and the height,respectively, of the first display. This is useful for extending thedisplay areas of, e.g., laptop or tablet computers that typically havesmall displays to enable the devices to be portable.

In some examples, each of the first and second displays are connected toa computer through a video cable. When the user connects the seconddisplay to the computer, the computer receives sensor signals anddetermines the relative positions of the two displays. The operatingsystem automatically determines the image to be shown on the seconddisplay so that the images can span properly across the first and seconddisplays. For example, the operating system determines what image toshow on the first and second displays so that a document can seamlesslyspan across the first and second displays.

In some examples, one or more additional displays can be used to extendone or more portions of the active display area of the first display inthe vertical direction, and one or more additional displays can be usedto extend one or more portions of the active display area of the firstdisplay in the horizontal direction.

In some examples, the first display is connected to a computer through avideo cable, and the second display is linked to the computer through awireless link. When the user positions the second display in thevicinity of the first display, sensors detect the presence of the seconddisplay and outputs a message on the first display asking whether theuser wishes to combine the second display with the first display to forma larger display. If the user confirms that the two displays should becombined, the computer establishes a wireless connection with the seconddisplay, e.g., using Bluetooth, Wi-Fi, wireless HDMI, or time-reversalcommunication techniques. The computer receives sensor signals anddetermines the relative positions of the two displays. The operatingsystem automatically determines the image to be shown on the seconddisplay so that the images can span properly across the first and seconddisplays. For example, the operating system determines what image toshow on the first and second displays so that the document canseamlessly span the first and second displays.

When the computer detects that the second display is removed from thevicinity of the first display, the computer provides a number of optionsto the user regarding how the second display is used. For example, oneoption is to use the second display as an independent display so thatthe first and second displays show content independent of each other.Another option is to turn off the second display. A third option is toshow content on the second display in a way that depends on the contentof the first display. For example, a document may be configured for usewith two displays such that when certain pages of the document are shownon a first display, certain content (certain illustrations or images) isshown on the second display. For example, when the user reads the firstchapter of a document on the first display, a drawing or imageassociated with the first chapter is shown on the second display. Whenthe user reads the second chapter of the document on the first display,the second display automatically shows a drawing or image associatedwith the second chapter.

In some implementations, a larger display can be formed by multiplesmaller displays in which each smaller display is a fully functionalcomputer that includes one or more microprocessors, memory (e.g.,dynamic random access memory or DRAM), one or more data storage devices(e.g., a hard drive or a flash drive), one or more communication modules(e.g., Wi-Fi, Bluetooth, or cellular), and a video controller. Thesmaller display can include a touch panel and can function similar to atablet computer. Circuitry for the microprocessor, memory, storagedevice, communication module, and the video controller can be fabricatedon the backside of the substrate that supports the pixels of the activedisplay area. Circuitry on the backside of the substrate can communicatewith circuitry on the front side of the substrate using signal linesthat pass through vias or holes in the substrate. Circuitry for themicroprocessor, memory, storage device, communication module, and thevideo controller can also be fabricated on one or more separatesubstrates that are bonded to the backside of the substrate thatsupports the pixels of the active display area. Circuitry on a firstsubstrate bonded to a second substrate can communicate with circuitry onthe second substrate through surface contacts between the first andsecond substrates. Each smaller display can have a thin and flatbattery, or have a coil to receive power transmitted wirelessly from apower source.

In the example above, each smaller display functions as a tabletcomputer having transparent (or semi-transparent) borders. Multipletablet computers can be combined so that the smaller displays of thetablet computers together form a larger display. One of the tabletcomputers functions as a leader, while the other tablet computersfunction as followers. The leader determines what image to show acrossthe displays. In some implementations, the leader determines what imageis shown on each of the followers, and sends image data to thefollowers. In some implementations, the leader determines the overallimage, sends the overall image to the followers, and each followerdetermines which portion of the overall image to shown on its display.The leader can communicate with the followers using wireless links, suchas Wi-Fi, Bluetooth, wireless HDMI, time-reversal communicationtechniques, or other wireless communication protocols.

In some implementations, the smaller displays each has a diagonal screensize of about 7, 10, 12, 14, 15, 17, 18, 24, 30, 40, or 60 inches.Multiple tablet computers can be combined to form a larger display. Thelarger display can have a horizontal, vertical, or diagonal dimensionof, e.g., 30 inches, 60 inches, 100 inches, 10 feet, 100 feet, 1000feet, or more.

When the smaller displays are combined to form a larger display, theimage on the larger display does not necessarily have to refresh as thesame rate as the smaller displays when the smaller displays operateindependently. For example, each tablet computer may have a smallerdisplay that refreshes at 60 Hz. When dozens of smaller displays arecombined to form a larger display, it may take some time for the leaderto transmit image data to all the followers, so the larger display mayrefresh the image at, e.g., 10 Hz or 1 Hz. In some examples, all thesmaller displays update the images at the same time so that a refreshedimage is shown properly across the larger display. However, it is alsopossible to update the images on the smaller displays in anon-synchronous manner.

In some implementations, when smaller displays are combined to form alarger display, different smaller displays may have different refreshrates. For example, the smaller displays near the center region of thelarger display may refresh at a faster rate than the smaller displaysnear the peripheral regions. For example, more resources may be devotedto updating the image data for the smaller displays near the centerregion of the larger display. For example, the leader may communicatewith the smaller displays near the center region of the larger displayusing a larger bandwidth, and communicate with the smaller displays nearthe peripheral regions of the larger display using a smaller bandwidth.

In some implementations, the user may determine which regions of thelarger display is shown with a higher refresh rate. In someimplementations, the operation system determines which portions of thelarger display requires a higher refresh rate (e.g., when showing video)and which portions of the larger display can use a lower refresh rate(e.g., when showing static or slowly changing text or images).

In some implementations, when smaller displays are combined to form alarger display, different smaller displays may show images usingdifferent resolutions. For example, the smaller displays near the centerregion of the larger display may show images at a higher resolution, andthe smaller displays near the peripheral regions of the larger displaymay show images at a lower resolution. For example, the smaller displaysshowing faster changing content may show images at a lower resolution,and the smaller displays showing slower changing content may show imagesat a higher resolution.

In some implementations, a first smaller display may communicate to asecond adjacent smaller display using a wired connection. For example,the smaller displays may have contacts at the sides, and when twosmaller display are place side-by-side, the contacts of the two smallerdisplays provide signal paths through which the two smaller displays canexchange data. The smaller displays may have magnets at the sides sothat two smaller displays couple at predetermined relative positions.This helps the alignment of the contacts. The contacts can be used totransmit power from one smaller display to another smaller display.

In some implementations, each smaller display has one or more magnets onthe backside of the display to help align the displays when one displayoverlaps another display.

Data can be transmitted through multiple displays using a relay fashion,for example, a first smaller display sends data to a second smallerdisplay, which sends data to a third smaller display, which sends datato a fourth smaller display, and so forth.

In some implementations, a first smaller display can communicate with asecond adjacent or overlapping smaller display using near fieldcommunication methods. For example, a first smaller display may have acommunication module having a coil that generates a magnetic fieldmodulated by a signal, in which the magnetic field is received by asimilar coil in the communication module of an adjacent or overlappingsecond smaller display. The received magnetic field is used by thesecond smaller display to generate a signal representing the signal sentby the first smaller display. The second smaller display can send datato the first smaller display in a similar manner. In someimplementations, each smaller display has coils near the left, right,top, and bottom borders so that the smaller display can communicate withanother display positioned near the left, right, top, and bottom border,respectively, using near field communication methods.

In some implementations, power can be relayed from one smaller displayto another smaller display wirelessly. For example, a first smallerdisplay is connected to a wired power line. The first smaller displaytransmits power wirelessly using, e.g., inductive coupling (such asresonant inductive coupling), capacitive coupling, or magneticresonance, to a second smaller display, which transmits power wirelesslyto a third smaller display, which in turn transmits power wirelessly toa fourth smaller display, and so forth.

In some implementations, a first smaller display can communicate with asecond adjacent or overlapping smaller display using opticalcommunication methods. For example, each smaller display may haveminiature light emitting devices and photo detectors at the back side ofthe display, and miniature photo detectors on the front side of thedisplay. When a second smaller display overlaps a first smaller display,the light emitting devices at the back side of the second smallerdisplay generate light modulated by a signal, in which the light isreceived by the photo detectors of the first smaller display. Thereceived light is used by the first smaller display to generate a signalrepresenting the signal sent by the second smaller display. The firstsmaller display can send data to the first smaller display by using oneor more pixels to generate light modulated by a signal, in which thelight is received by the photo detectors at the back side of the secondsmaller display. In some implementations, each smaller display has lightemitting devices and photo detectors at the back side near the left,right, top, and bottom borders, and photo detectors at the front sidenear the left, right, top, and bottom borders, so that the smallerdisplay can communicate with another smaller display positioned near theleft, right, top, or bottom border, respectively, using opticalcommunication methods. Each of the photo detectors at the front side canoccupy an area that is a fraction of the area of a pixel.

In some implementations, each smaller display has integrated solar cellsthat can generate power from received external light.

In some implementations, a computer hosts a more powerful processor toprocess image data sent to the multiple smaller displays, and eachsmaller display has a video controller that controls the pixels to showan image according to the received image data. The video controller doesnot need to perform complex calculations and can be consume a smalleramount of power. The computer can be made larger with a larger batteryor power supply, whereas the smaller displays can be made thin and lightand easily portable. The computer can communicate with the smallerdisplays wirelessly using a communication method that focuses signalsintended for particular displays toward those particular displays. Forexample, an antenna array at the computer can be used to direct awireless signal toward one or more particular smaller displays.Time-reversal wireless communication techniques can be used for theuplink and downlink between the computer and the smaller displays.

In some implementations, the smaller displays have touch screens and theuser can apply touch gestures to indicate how the smaller displaysshould interact with one another. For example, when an upper displayoverlaps a lower display, the user can use a first gesture, such asswiping two fingers from the upper display to the lower display, toindicate that the two displays should combine to form a larger display.The user can use a second gesture, such as drawing an “X” across theborder of the upper display overlapping the lower display, to indicatethat the two displays should operate independently and not combine toform a larger display.

In some implementations, the user can swipe in from a border of asmaller display to access a menu that provides various configurationoptions, such as selecting the smaller display to be a main display or asecondary display. The menu can also provide options to allow the userto select whether the smaller display should join in a larger display,or break away from the larger display.

In some implementations, suppose a document is shown across a firstsmaller display and a second smaller display, when the second smallerdisplay breaks away from the first smaller display, the document isshown only on one of the displays and is removed from the other display.The user can select which display to show the document.

In some implementations, suppose a document is shown across a firstsmaller display and a second smaller display, when the second smallerdisplay breaks away from the first smaller display, the document isshown on both displays. The two displays are linked such that when theuser edits the document shown on the first display, the document shownon the second display is automatically updated. The user can scrollthrough the document on the first display and the second displayindependently. Thus, the first display can show one page of the documentwhile the second display shows a different page of the document. Thefirst and second displays can also both show the same page of thedocument. For example, the document can be a patent application, thefirst display can show the detailed description of the patentapplication and the second display can show the figures of the patentapplication. The reference numbers in the detailed description can belinked to the reference numbers in the figures, so that when the usermodifies the reference numbers in the figures shown in the seconddisplay, the reference numbers in the detailed description shown in thefirst display are automatically updated.

In some implementations, a larger display can be formed by a combinationof two or more smaller displays under the control of multiple operatingsystems. For example, a first tablet computer, a second tablet computer,a third tablet computer, and a fourth tablet computer each having adisplay with transparent (or semi-transparent) borders can combine toform a larger display, in which the first tablet computer runs a firstoperating system (e.g., Apple iOS or Mac OS X), the second tabletcomputer runs a second operating system (e.g., Microsoft Windows), thethird tablet computer runs a third operating system (e.g., Android), andthe fourth tablet computer runs a fourth operating system (e.g., Linux).The user selects one tablet computer as the main computer. The maintablet computer determines what image to show on the larger display, andsends image data to the other tablet computers to show portions of theimage on the displays of the other tablet computers.

In some implementations, multiple smaller displays are combined to forma larger display, in which each smaller display is controlled wirelesslyby a computer. For example, a first smaller display is controlledwirelessly by a first computer that runs a first operating system, e.g.,Apple iOS or Mac OS X. The second smaller display is controlledwirelessly by a second computer that runs a second operating system,e.g., Microsoft Windows. The third smaller display is controlledwirelessly by a third computer that runs a third operating system, e.g.,Android. The fourth smaller display is controlled wirelessly by a fourthcomputer that runs a fourth operating system, e.g., Linux. The userselects one computer as the main computer. The main computer determineswhat image to show on the larger display, and sends image data to theother computers to show portions of the image on the smaller displayscontrolled by the other computers. The main computer can send image datato the other computers using a wireless communication method, e.g.,Wi-Fi, Bluetooth, or time-reversal techniques, or a wired communicationmethod, e.g., Ethernet.

In some implementations, when the smaller displays are combined to forma larger display, the main computer determines a coordinate system forthe larger display, the coordinates of the larger image in thecoordinate system, and the coordinates of each smaller display on thecoordinate system, and sends the information to the other computers.Each time a smaller display is moved relative to the other smallerdisplays, the main computer determines updated coordinates for thesmaller display, and sends the updated coordinates to the computer thatcontrols the smaller display. For each large image to be shown on thelarger display, the main computer sends the image data and coordinatedata for the large image to each of the other computers. Because eachcomputer has information about the coordinates of the large image andthe coordinates of the smaller display controlled by the computer in thecoordinate system, the computer can determine which portion of the largeimage should be shown on the smaller display. The main computer sends asynchronization signal to the other computers so that all the computerscan update the images shown on the smaller displays at the same time.

In some implementations, each smaller display has a graphics memory tostore the image data to be shown on the smaller display. The smallerdisplay has a video controller that controls the pixels of the displaybased on the image data stored in the graphics memory. When an image onthe smaller display needs to be modified, the computer writes image datato the graphics memory of the smaller display. This is useful when thesmaller display is showing images that are mostly static and only asmall portion of the images change, such as when the user is processingtext or still photographs. When only a small portion of the imagechanges, only a small amount of data in the graphics memory need to beupdated, so the computer only needs to send a small amount of image datato the display.

In some implementations, a first smaller display is controlled by afirst computer, and a second smaller display is controlled by a secondcomputer. The first and second smaller displays are combined to form alarger display. The larger display shows a large desktop spanning thefirst and second smaller displays. A first window is provided to show asmaller desktop associated with the first computer, in which the smallerdesktop shows icons for accessing files and programs accessible to thefirst computer. A second window is provided to show a smaller desktopassociated with the second computer, in which the smaller desktop showsicons for accessing files and programs accessible to the secondcomputer. The image content of the first window is generated by thefirst computer, and the image content of the second window is generatedby the second computer. Assume that the first computer is the maincomputer, then the user interacts with first computer to providekeyboard and mouse pointer inputs. When the user interacts with items inthe first window, the first computer functions the same way as if thecomputer is controlling just one display. For example, if the userclicks on an icon, the icon is selected and highlighted, and if thedouble-clicks on an icon representing a program, the program is executedand displayed in the first window.

When the user interacts with items in the second window (e.g., throughkeyboard and mouse inputs), the first computer sends the interactions tothe second computer and the second computer functions the same way as ifthe user is interacting with the second computer. For example, if theuser clicks on an icon in the second window, the icon is selected andhighlighted, and if the double-clicks on an icon representing a programin the second window, the program is executed and displayed in thesecond window. The second computer generates the image content for thesecond window, and sends the image content to the first computer. Thefirst computer generates the large image to be shown on the largerdisplay, in which the large image incorporates the image content for thesecond window. After the large image is generated by the first computer,the first and second computers control the respective smaller displaysto show portions of the large image using the techniques previouslydescribed.

Suppose the user wants to copy a file stored at the second computer andsave the file to a directory at the first computer. The user enters afirst command to copy a file of the second computer (e.g., in Windowssystem, by right-clicking an icon in the second window representing thefile and selecting the “copy” command from a pop-up menu), the firstcomputer receives the user command and sends the command to the secondcomputer. The second computer generates a copy of the file. The userenters a second command to save the file to a directory of the firstcomputer (e.g., by double-clicking an icon in the first window thatrepresents the directory to open the directory and selecting the “save”command from the file menu). The first computer receives the secondcommand and sends the second command to the second computer. The secondcomputer sends the copy of the file to the first computer, and the firstcomputer saves the copy of the file in the directory of the firstcomputer selected by the user.

The user may open additional windows, in which each window is controlledby either the first computer or the second computer. For example, if theuser executes a first program on the first computer, a third window maybe shown for the first program. When the user interacts with the itemsin the third window, the first computer performs relevant functionsbased on the user interaction. The first computer generates the imagecontent for the third window, and updates the large image incorporatingthe image content of the third window. If the user executes a secondprogram on the second computer, a fourth window may be shown for thesecond program. When the user interacts with the items in the fourthwindow, the first computer sends the interactions to the secondcomputer, and the second computer functions as if the user isinteracting with the second computer. The second computer generates theimage content for the fourth window, sends the image content to thefirst computer, and the first computer updates the large imageincorporating the image content for the fourth window.

In some implementations, the region of the large desktop outside of thefirst and second windows represents a temporary desktop managed by themain computer (in this example, the first computer). When an icon isplaced in the large desktop, the icon is linked to a resource in eitherthe first computer or the second computer. For example, an icon for aprogram stored in the second computer can be placed on the largedesktop. When the user double-clicks on the icon, the first computersends the command to the second computer, and the second computerexecutes the program.

In some implementations, when a third smaller display controlled by athird computer is joined with the first and second smaller displays toform a larger display, a fifth window is provided to show a smallerdesktop associated with the third computer. Accessing the items in thefifth window can be performed in a similar manner as accessing the itemsin the second window.

In some implementations, a large display may represent a central hub forvarious electronic devices owned by a user. For example, the largedisplay may show a first window associated with a desktop computer, asecond window associated with a first laptop computer using Windowsoperating system, a third window associated with a second laptopcomputer using Mac OS X operating system, a fourth window associatedwith a first mobile phone using iOS operating system, a fifth windowassociated with a second mobile phone using Android operating system, asixth window associated with a tablet computer using iOS operatingsystem, and a seventh window associated with a work station using Linuxoperating system. Combining multiple smaller displays to form a largerdisplay, the display area can be easily expanded to accommodate themultiple windows associated with multiple devices. The large displaywith multiple windows associated with multiple devices allows the userto conveniently share resources among the devices, such as copying afile from one device to another device, or executing two programs fromtwo devices and showing the programs side-by-side on the large display.In this example, the large display can be a single display (i.e., allthe pixels are supported by a single substrate) or be formed from acombination of multiple smaller displays.

For example, the user may perform a computation-intensive imageprocessing operation on a Linux workstation to generate a processedimage, and execute a word processing program on a Windows laptop toprepare a report. The user can show the processed image in a firstwindow associated with the Linux workstation and show the report in asecond window associated with the Windows laptop, in which the first andsecond windows are both shown on the large display. The user can copythe processed image in the first window and paste it in the report shownin the second window. In response to the copy command, the Linuxworkstation generates a copy of the processed image. In response to thepaste command, the Linux workstation sends the copy of the processedimage to the Windows laptop, and the Windows laptop pastes the processedimage into the report.

In some implementations, when a resource (such as a document or an imagefile) is transferred from one device using a first operating system to asecond device using a second operating system, adjustments are made tothe resource so that it can be processed by the second operating system.

In some implementations, a hub server is used as a bridge between thevarious devices and to control images shown on the large display. Forexample, the user may interact with the hub server, which communicateswith a Linux workstation and a Windows laptop. When the user attempts tocopy a processed image generated by an image processing programexecuting on the Linux workstation to a report generated by a wordprocessing program executing on the Windows laptop, the Linuxworkstation makes a copy of the processed image and sends the copy ofthe processed image to the hub server, the hub server sends theprocessed image to the Windows laptop, and the Windows laptop pastes theprocessed image into the report. If the large display is formed by acombination of smaller displays, the hub server may control the smallerdisplays to show relative portions of the larger image shown on thelarge display.

In some implementations, a large display can be formed by a combinationof multiple smaller displays, in which a first computer controls two ormore of the smaller displays, and a second computer controls two or moreof the smaller displays. The computer can be, e.g., a workstation, adesktop computer, a laptop computer, a tablet computer, or a smartphone.

A security procedure may be implemented when the large display is usedas a hub for enabling the user to transfer resources from one computerto another computer. For example, if the user is interacting with thefirst computer to access resources of the second computer for the firsttime, the second computer may request confirmation that user intends toallow the first computer to access resources from the second computer.In some implementations, when a smaller display controlled by a devicejoins other smaller displays to form a larger display, the smallerdisplay may show a message asking the user whether the user wishes toallow other devices to access resources on the device.

The determination of relative positions of displays and calculation ofthe coordinates of pixels described above can be implemented usingsoftware for execution on a computer. For instance, the software formsprocedures in one or more computer programs that execute on one or moreprogrammed or programmable computer systems (which may be of variousarchitectures such as distributed, client/server, grid, or cloud) eachincluding at least one processor, at least one data storage system(including volatile and non-volatile memory and/or storage elements), atleast one input device or port, and at least one output device or port.The software may form one or more modules of a larger program, forexample, that provides other services related to the generation ofimages to be shown on the displays. In the example described above inwhich the user living in Boston can view scenes from Paris on a largedisplay formed by multiple small displays, the server computer providingthe images for the large display can be a cloud server. In someexamples, the cloud server determines the relative positions of thesmall displays, determines the image contents to be shown on each smalldisplay, and sends the image contents to the small displays through thenetwork. In some examples, the cloud server determines the large imageto be shown on the large display, and sends the large image to thedisplay controller of the local user computer. The local user computerdetermines the relative positions of the small displays, and determinesthe portion of the large image to be shown on each small display.

The software may be provided on a medium, such as a CD-ROM, readable bya general or special purpose programmable computer or delivered (encodedin a propagated signal) over a network to the computer where it isexecuted. All of the functions may be performed on a special purposecomputer, or using special-purpose hardware, such as coprocessors. Thesoftware may be implemented in a distributed manner in which differentparts of the computation specified by the software are performed bydifferent computers. Each such computer program is preferably stored onor downloaded to a storage media or device (e.g., solid state memory ormedia, or magnetic or optical media) readable by a general or specialpurpose programmable computer, for configuring and operating thecomputer when the storage media or device is read by the computer systemto perform the procedures described in this document. The inventivesystem may also be considered to be implemented as a computer-readablestorage medium, configured with a computer program, where the storagemedium so configured causes a computer system to operate in a specificand predefined manner to perform the functions described in thisdocument.

A number of embodiments of the description have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the description. Forexample, some of the steps described above may be order independent, andthus can be performed in an order different from that described. It isto be understood that the foregoing description is intended toillustrate and not to limit the scope of the description, which isdefined by the scope of the appended claims. Other embodiments arewithin the scope of the following claims.

1.-20. (canceled)
 21. A system for assisting in learning, the systemcomprising: a larger display formed by two or more smaller displays,each of the smaller displays comprises an active display regioncomprising individually controllable pixels; at least one sensor togenerate sensing signals having information useful in determiningrelative positions of the smaller displays; and a display controllerconfigured to determine relative positions of the smaller displays basedon the sensing signals generated by the at least one sensor, determine alarger image for the larger display, and control each of the smallerdisplays to show a portion of the larger image such that the largerimage spans across the smaller displays; wherein a first portion of theimage represents a first learning material, and a second portion of theimage represents a second learning material related to the firstlearning material. 22.-219. (canceled)
 220. The system of claim 21 inwhich the at least one sensor comprises a camera that captures an imageof pixels of the smaller displays, and the display controller isconfigured to use outputs from the camera to determine the relativepositions of the smaller displays.
 221. The system of claim 21 in whichat least one of (i) the first learning material comprises mathematicalexercises, and the second learning material comprises at least onearticle related to the mathematical exercises; (ii) the first learningmaterial comprises a timeline of events, and the second learningmaterial comprises at least one article related to the events; (iii) thefirst learning material comprises at least one mathematical formula, andthe second learning material comprises at least one graph related to theat least one mathematical formula; (iv) the first learning materialcomprises at least one of a foreign language article or a foreignlanguage exercise, and the second learning material comprises at leastone of a foreign language dictionary, a foreign language thesaurus, or aforeign language grammar guide; or (v) the first learning materialcomprises at least one map of a geographical region, and the secondlearning material comprises at least one article related to thegeographical region.
 222. An apparatus comprising: a first displaydevice comprising a first active display region comprising individuallycontrollable pixels; and a transparent or semi-transparent border regionhaving a transmissivity of at least 10% for visible light; a seconddisplay device comprising a second active display region comprisingindividually controllable pixels, in which the first display deviceoverlaps the second display device such that the transparent orsemi-transparent border region of the first display device covers atleast a portion of the second active display region; and a displaycontroller to control the first and second display devices to show animage that spans the first and second display devices, wherein thedisplay controller is configured to control the second display device tomodify at least one of contrast, hue, or color of pixels in the secondactive display region that is covered by the transparent orsemi-transparent border region of the first display device to compensatea visual effect caused by the transparent or semi-transparent borderregion.
 223. An apparatus comprising: a first display device comprisinga first active display region comprising individually controllablepixels; a second display device comprising a second active displayregion comprising individually controllable pixels; a sensor to detect aposition of the first device relative to the second display device; anda display controller to control the first and second display devices toshow an image that spans the first and second display devices, in whichthe display controller is configured to control the first and seconddisplay devices based on information about the relative positions of thefirst and second devices.
 224. The apparatus of claim 223 in which thesensor comprises one or more light sensors on a backside of the firstdisplay device for detecting light from the second display device, inwhich the light from the second display device detected by the one ormore light sensors on the backside of the first display device is usedin determining the position of the first display device relative to thesecond display device.
 225. The apparatus of claim 224 in which thesensor comprises a first series of light sensors and a second series oflight sensors on the backside of the first display device for detectinglight from the second display device, in which the light from the seconddisplay device detected by the first and second series of light sensorsis used in determining the position of the first display device relativeto the second display device.
 226. The apparatus of claim 223,comprising at least one of a mobile phone, a tablet computer, a notebookcomputer, a desktop computer monitor, a television, a game controller,or an electronic book, wherein the second display device is part of theat least one of the mobile phone, the tablet computer, the notebookcomputer, the desktop computer monitor, the television, the gamecontroller, or the electronic book.
 227. The apparatus of claim 223 inwhich the first display device comprises at least one of a plasmadisplay, an electroluminescent display, a liquid crystal display, anorganic light emitting diode display, a quantum dot display, aninterferometric modulator display, a carbon nanotube-based display, adigital micro shutter display, a surface-conduction electron-emitterdisplay, a field emission display, or an electronic ink display. 228.The apparatus of claim 223 in which the apparatus comprises least one ofa window simulator, a flight simulator, a car simulator, a submarinesimulator, or a space ship simulator, and the first and second displaydevices are configured to show images that simulate scenes that a userwould see when looking through a window, flying an airplane, driving acar, diving in a submarine, or flying in a space ship, respectively.229. The apparatus of claim 223, comprising additional display devicesthat together with the first and second display devices collaborativelyform a larger display, in which the display controller is configured todetermine the position of each of the display devices relative to atleast one other display device, and determine a life-size image to beshown across the multiple display devices based on the relativepositions of the display devices.
 230. The apparatus of claim 223,comprising additional display devices that together with the first andsecond display devices collaboratively form a larger display having ahorizontal, vertical, or diagonal dimension of at least 100 inches, inwhich the display controller is configured to determine the position ofeach of the display devices relative to at least one other displaydevice, and determine an image to be shown across the multiple displaydevices based on the relative positions of the display devices.
 231. Theapparatus of claim 223, comprising additional display devices thattogether with the first and second display devices collaboratively forma larger display having a horizontal, vertical, or diagonal dimension ofat least 10 feet, in which the display controller is configured todetermine the position of each of the display devices relative to atleast one other display device, and determine an image to be shownacross the multiple display devices based on the relative positions ofthe display devices.
 232. The apparatus of claim 223, comprisingadditional display devices that together with the first and seconddisplay devices collaboratively form a larger display having ahorizontal, vertical, or diagonal dimension of at least 100 feet, inwhich the display controller is configured to determine the position ofeach of the display devices relative to at least one other displaydevice, and determine an image to be shown across the multiple displaydevices based on the relative positions of the display devices.
 233. Theapparatus of claim 223, comprising additional display devices thattogether with the first and second display devices collaboratively forma larger display having a horizontal, vertical, or diagonal dimension ofat least 1000 feet, in which the display controller is configured todetermine the position of each of the display devices relative to atleast one other display device, and determine an image to be shownacross the multiple display devices based on the relative positions ofthe display devices.
 234. The apparatus of claim 223 in which the firstdisplay device comprises a U-shaped active display area that at leastone of overlaps portions of, or aligns with, three edges of the activedisplay area of the second display device.
 235. The apparatus of claim223 in which at least one of (i) the first display device is configuredto show an article without sponsored content or with reduced sponsoredcontent, and the second display device is configured to show sponsoredcontent, or (ii) the second display device is configured to show anarticle without sponsored content or with reduced sponsored content, andthe first display device is configured to show sponsored content. 236.The apparatus of claim 223 in which the first and second display devicescomprise three-dimensional displays, and the display controller isconfigured to control the first and second display devices to show athree-dimensional image that spans the first and second display devices.237. The apparatus of claim 223 in which at least one of the firstactive display region or the second active display region has a shape inthe form of a circle, an oval, a triangle, a rhombus, a parallelogram, atrapezium, a convex polygon, a concave polygon, or an irregular shape.238. The apparatus of claim 223 in which the first display devicecomprises at least one of an adhesive or a friction pad at a backside ofthe first display device configured to reduce movement between the firstand second display devices after the first display device is positionedto overlap the second display device.
 239. The apparatus of claim 238 inwhich the first display device comprises a synthetic gecko adhesive on abackside of the first display panel.
 240. The apparatus of claim 223 inwhich the first display device comprises an electro-adhesive pad on abackside of the first display panel.
 241. The apparatus of claim 240 inwhich the display controller is configured to apply a first signal tothe electro-adhesive pad to cause the electro-adhesive pad to adhere tothe second display device.
 242. The apparatus of claim 241 in which thedisplay controller is configured to apply a second signal to theelectro-adhesive pad to cause the electro-adhesive pad to be releasedfrom the second display panel.
 243. The apparatus of claim 241 in whichthe display controller is configured to, in response to a motion sensordetecting a movement indicating at least a portion of the first displaydevice is moving relative to the second display device, apply a secondcontrol signal to the electro-adhesive pad to cause the electro-adhesivepad to at least one of (i) be released from the second display panel, or(ii) reduce an adhesion force between the electro-adhesive pad and thesecond display panel.
 244. The apparatus of claim 243 in which thedisplay controller is configured to, after the electro-adhesive pad isreleased from the second display device or reduces the adhesion forcebetween the electro-adhesive pad and the second display device, upondetermining that the first display device is moved to a second positionrelative to the second display device and the electro-adhesive pad stilloverlaps the second display device, apply a third control signal to theelectro-adhesive pad to cause the electro-adhesive pad to increase theadhesion force between the electro-adhesive pad and the second displaypanel.
 245. The apparatus of claim 223 in which the first display devicecomprises a transparent or semi-transparent border region having atransmissivity of at least 10% for visible light, the first displaydevice overlaps the second display device such that the transparent orsemi-transparent border region of the first display device covers atleast a portion of the second active display region, and ananti-reflective coating on a back side of the transparent orsemi-transparent border region to reduce reflection of light emittedfrom the second active display region covered by the transparent orsemi-transparent border region.
 246. The apparatus of claim 223 in whichthe first display device comprises a transparent or semi-transparentborder region having a transmissivity of at least 10% for visible light,the first display device overlaps the second display device such thatthe transparent or semi-transparent border region of the first displaydevice covers at least a portion of the second active display region,and the display controller is configured to control the second displaydevice to modify a property of pixels in the second active displayregion that is covered by the transparent or semi-transparent borderregion of the first display device to compensate a visual effect causedby the transparent or semi-transparent border region.
 247. The apparatusof claim 246 in which the display controller is configured to controlthe second display device to modify at least one of brightness,contrast, hue, or color of pixels in the second active display regionthat is covered by the semi-transparent border region of the firstdisplay device to compensate the visual effect caused by the transparentor semi-transparent border region.
 248. The apparatus of claim 223,comprising a ship that includes the first display device, the seconddisplay device, the sensor, the display controller, and a camera tocapture images of an environment of the ship, in which the displaycontroller causes at least portions of the images of the environment ofthe ship to be shown on the first and second display devices.